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lliVESTIGA TION OF ELECTRIC FISHES FINAL REPORT - PHASE I by Prepared under; J Contract 28 January '1974 SUMMARY The African fresh water weakly electric fish Gnathonemus petersii has been investigated. The study has been directed toward the intradermal sensory system with emphasis on the electroreceptors. Three types of electroreceptors have been identified. The autorhymic activity of these electrore ceptors has been recorded. The variation of the electric signal of the electric organ have been recorded for three specimens of Gnathonemus petersii as a rest activity and maximum signal rate when a metallic object has been placed near the fish. The number and density of different kinds of electroreceptors in the dermis have been counted and plotted against rate change and their sensitivity to a metallic object. The preparation of the large tank experiments have been re ported and the newly developed instrumentation is mentioned. CONTENTS 1. INTRODUCTION . . . • . • • • . . . . • . . • . . • • • • . . • • • • . . 1 2. METHODS AND INSTRUMENTATION . . . . . . . . . • • . . . • . 2 3. RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 4. LARGE WATER TANK PREPARATION FOR EXPERIMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 FIGURES Figure 1 African fresh water weakly electric fish Gnathonemus petersii ..............••.... 3 2 Electric fish Gnathonemus petersii in a lucite restraining tray provided with stainless steel electrodes . . . . . . . . . . . . . . . . . . .. . . . . . . . . 3 3 Microelectrode amplifier .....•.•.......•. 5 4 Microelectrode amplifier and support in its shielding tube . . . . . . . . . . . . . . . . . . . . . . . . . 6 5 Microelectrode amplifier ready to be put in the shielding tube, face side ...•...........•.. 6 6 Microelectrode amplifier ready to be put in the shielding tube, back The image displays text over a dark background, with a graphic of a vault door on the left. The text describes that the document was obtained from "The Black Vault," an online database of declassified government documents, and specifically mentions the "MKULTRA/Mind Control Collection." The vault graphic, with its metallic sheen and intricate locking mechanisms, metaphorically represents a secure repository of sensitive information. No photographs, handwritten annotations, signatures, forms, diagrams, tables, or experimental procedures are visible. There are no visible official stamps or redactions on this page. This page is a title page for a report. It features the title "INVESTIGATION OF ELECTRIC FISHES" within a bordered box. Below the title, it states "FINAL REPORT - PHASE I" and "by" followed by an empty space for a name. Further down, it indicates "Prepared under:" and lists "Contract" in an empty field, followed by the date "28 January 1974". At the bottom right corner, there is a handwritten annotation within a circle that reads "259". There are no photographs, diagrams, stamps, or filled-in forms visible on this page. . . . . . . . . . . . . . . . . . . . . . . 6 5 Microelectrode amplifier ready to be put in the shielding tube, face side ...•...........•.. 6 6 Microelectrode amplifier ready to be put in the shielding tube, back side .•.•.••.........• 7 7 Microelectrode amplifier input and output wave form and gain (see Table 2) • • • • • • • • • • • ••••• 11 8 Microelectrode amplifier input and output wave form and gain (see Table 2) •••. ~ .•••••••••. 11 9 Microelectrode amplifier input and output wave form and gain (see Table 2) •••.•••••••••••• 12 10 Microelectrode amplifier input and output wave form and gain (see Table 2) •••••••••••••••• 12 11 Microelectrode amplifier input and output wave form and gain (see Table 2) ••••••.••••••••• 13 iv ----------- -Pa)o,ow 12 Microelcctrode amplifier input and output wave form and gain (see Table 2) ••.............. 13 13 Microelectrode amplifier input and output wave form and gain (see Table 2) ••.•...•..•.•..• 14 14 Microelectrode amplifier input and output wave form and gain (see Table 2) ••.•.....••..••. 14 15 Microelectrode amplifier input and output wave form and gain (see Table 2) .•••.•.•.•.•.•.. 15 16 Microelectrode amplifier input and output wave form and gain (see Table 2) •••........•..•. 15 17 Microelectrode amplifier input and output wave form and gain (see Table 2) .•..•........•••. 16 18 Microelectrode amplifier input and output wave- forln and gain . . . . . . . . . . . . . . . . . . . . . . . . . 16 19 Tuberous organ (electroreceptor) of Gnathonemus petersii . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 20 The electric sensory fields of Gnathonemus petersii . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 21 Limits of the electroreceptors sensory fields of Gnathonemus petersii . ·. .•.•••••..•....... 20 22 Different types of mormyromasts: a. tuberous organ, b. A-mormyromast, c. B -mormyromast (top and cut view) .••....•..•............ 21 . 23 The lateral line nerves of the electric fish Gnathonemus petersii .•.....•.•..•....... 22 24 Comparison between sensitivity and density of the sensory fields of Gnathonemus petersii . ·. .•.•••••..•....... 20 22 Different types of mormyromasts: a. tuberous organ, b. A-mormyromast, c. B -mormyromast (top and cut view) .••....•..•............ 21 . 23 The lateral line nerves of the electric fish Gnathonemus petersii .•.....•.•..•....... 22 24 Comparison between sensitivity and density of the electroreceptors of Gnathonemus petersii in the epidern1is . . . .. . . . . . . . . . . . . . . . . . . . . . . . . 24 v ·- Figure 25 Autorhytmic activity of the electroreccptors of Gnathonemus petersii: a. 500 Hz calibration signal, b. elcctroreceptors near the chin, c. electroreceptors near the eye . . • • . . . . . . • . •. 24 26 Electric activity from the nervus lateral anterior innervating receptor near the proboscis of a mech anical displacement on the chin of Gnathonemus petersii when the proboscis has been moved upwards: = a. time marks 50 Hz, b. electric activity in the nerve, c. movement of the chin proboscis ..•••• 25 27 12 ft. diameter fiberglass tank provided with heat ing, filtering, countercurrent aeration and double rails for electrode support ......•.•....•.. 27 28 Heating tank provided with automatic control of temperature to 0. 0 1 °C • • • • • • • • • • . • • • • • • • • 27 29 Differential amplifier hanging over the water tank . 28 30 Close look at the differential amplifier used in con junction with the electrodes in the water tank to · record electric activity of electric fishes ...... . 28 31 Differential amplifier with remote control. Ampl. factor = x 4000, noise = 1 microvolt . . ....... . 29 32 Devices for restraining electric fishes in the water tank . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 vi 1. INTRODUCTION In our letter report of 24 July 1973 we mentioned our interest in the mormyrid electric fishes. One of our reasons is that they have an electrical quantifiable behavioral variable. The rate and amplitude of their electric signal changes when they are electrically stimulated or discontinuities ap pear in their electromagnetic field. In our study of their electroreceptors we found some mechanoreceptors The provided image is a scanned document page, predominantly featuring text. The text is centered on the page and appears to be a summary of research on electric fish. There are no images, photographs, handwritten annotations, signatures, official stamps, forms, diagrams, schematics, organizational charts, tables, structured data, or visual evidence of experimental procedures, equipment, or facilities. The only visual elements besides the text are some faint, almost unnoticeable dashes and dots that appear to be artifacts from the scanning or printing process, primarily located in the upper and lower portions of the page. There are no visible redactions or obscured content. This page is the table of contents for a document. It lists four numbered sections: Introduction, Methods and Instrumentation, Results, and Large Water Tank Preparation for Experiments. Each section is followed by a series of dots and a page number. The page also contains the roman numeral "iii" at the bottom, indicating it is the third page of a section. There is no photographic, handwritten, stamped, or diagrammatic content present. in the mormyrid electric fishes. One of our reasons is that they have an electrical quantifiable behavioral variable. The rate and amplitude of their electric signal changes when they are electrically stimulated or discontinuities ap pear in their electromagnetic field. In our study of their electroreceptors we found some mechanoreceptors on the chin having a close morphology to the Lorenzini ampulla, a multisensory receptor. This fact confirms our findings with respect to the Lorenzini ampulla functions from our previous research. 1 ----------------- ,~~.--~ -----' - 2. METHODS AND INSTRUMENTATION Three specimens of Gnathonemus petersii (Fig. 1) a mormyrid fresh water, weakly electric fish from Africa, have been used in our experiments. The fishes were in our laboratory for three months and each one held se parately in 15 gallons aquaria. The water pH was around 6. 9 and the tem peratw·e was 24°C. A lucite tray with stainless steel pick-up contacts half embedded in the lucite wall were used to restrain the fishes during experiments for as sessing the limits of the repetition rate of their electric activity (Fig. 2). The microelectrode amplifiers previously developed had a drawback, namely, when changes in the input resistance occurred, the offset potentio meter had to be reset. When very sensitive and delicate microelectrode recordings were made, resetting of the offset potentiometer was sometimes an impossible job owing to the diameter of the microelectrode of 0. 5 microns. The microelectrode amplifier is also the direct support for the microelectrode proper. Unfortunately until recently nothing was available for the building of a microelectrode amplifier having all the necessary specs: high input im pedance with low capacitance, a reasonable amplification factor, a low output impedance, very low noise factor and an insensitivity to change in input re sistance from 50 ohms to 1 meghom. It also had to use little power and have a frequency range from DC to 50,000 repetition rate square wave or from DC to 1 MHz, with an amplification factor flat within ma.ximum 3 dB. We finally succeeded in building such an amplifier, which could mean a successful recording under most adverse conditions of small DC or AC 2 Fig. 1. African fresh water weakly electric fish Gnathonemus petersii. •' ·.. .,• ,. .. ..:;..1 t' ~------~----~-., ~-··- Fig. 2. Electric fish Gnathonemus pctcrsii in a lucite tray provided with stainless steel rcstrainin~ electrodes. 3 - sit:,'lmls from the elcctrorcceptors of electric conditions of small DC or AC 2 Fig. 1. African fresh water weakly electric fish Gnathonemus petersii. •' ·.. .,• ,. .. ..:;..1 t' ~------~----~-., ~-··- Fig. 2. Electric fish Gnathonemus pctcrsii in a lucite tray provided with stainless steel rcstrainin~ electrodes. 3 - sit:,'lmls from the elcctrorcceptors of electric fishes, and which docs not need to reset the offset potentiometer. The amplifiers we used wttil now were the best which could be built, but they were far from the capabilities of the new microelcctrodc amplifier, which incidentally, could be used in our simulation of the electric fish capabilities because of its low noise and very large bandwidth, combined with an insensitivity to change in input im pedance. Figure 3 shows the schematic of the new amplifier, and Figs. 4, 5 and 6, are actual photos of the amplifier. 4 -,_ A ~ ({ ;:, •·- 0 ~ ~ ~ \.!) ~ ..... .-.... / I • /~ I --'!''-~I -----~-----.1.- ~-~-----..... ---;i-"/;1:(--~to -+l-. \ .>~ r---<----L-L~ l, I -'rM'/ I / r--\ ----_...;;;~ ::::l.r)i:J----- :::: ; '>.J \ gr.J \ \ ... 3 I.J -Q---"V 0 :::: :)(. N. . 0- 5 M.icroe lectrode amplifier and support Fig. 4. in its shielding tube. M.icroe lcctrode an1plifier ready to be put Fig. 5. in the shielding tube, face side. 6 Microe lee trade amplifier ready to be put in Fig. 6. the shielding tube, back side. 7 3. RESULTS The specimens of the electric fish Gnathonemu..c; petersii were put in the lucite tray, using their own aquarium water and air was provided through a special glass tube. The temperature of the water has been recorded. After a few minutes accommodation to their environment the electrodes correspond ing to the head and tail of the fish, were connected to an amplifier, to the oscilloscope and to a cormter. The rest activity has been read on the cormter. Then a carbon steel rod (diam ~ 3 mm) has been immersed in the tray in the proximity of the fish. The repetition rate increased significantly and a read ing of the counter has been made. Figure 2 shows the fish in the tray. Table 1 shows the repetition rates of the signals. There is a ratio that could go to 1:23 (Fish No. 3) between the minimum and the maximum rate of the signal. Subsequent experiments could show how the repetition rate and This page displays a list of figures from a document, titled "FIGURES." The table format includes "Figure" and "Page" columns, detailing 11 figures with their respective descriptions and page numbers. The descriptions refer to "African fresh water weakly electric fish," "Microelectrode amplifier," and "Microelectrode amplifier input and output waveform and gain (see Table 2)." The page is a typed document with some inconsistencies in spacing. No photographs, handwritten annotations, stamps, forms, diagrams, schematics, organizational charts, or visual evidence of experimental procedures are present. been made. Figure 2 shows the fish in the tray. Table 1 shows the repetition rates of the signals. There is a ratio that could go to 1:23 (Fish No. 3) between the minimum and the maximum rate of the signal. Subsequent experiments could show how the repetition rate and amplitude of the signals are related to the size, composition and proximity of the objects The microelectrode amplifier has been checked for its frequency and gain response using a Wavetek wave generator, attenuator and a Tektronix Oscilloscope type No. 555. The upper trace of the photos shows the input waveform and lower trace shows the output waveform of the amplifier. Both sine waves and square waves have been used. Table 2 shows the waveform, amplitude, gain and input resistance. Six photos were made for 50 ohms input resistance and six photos were made for 1 megohm input resistance. 8 I 1 TABLE 1 Rest and Maximum Repetition Rate of the Electric Signal of Three Specimens of Gnathonemus petersii I Signal Date Weight Water Fish of of Fish Rest Max. Amplitude Temp. No. Recording in Grams Rep. Rate Rep. Rate mV in °C Instrumentation 1 8/12/73 15 15 136 500 20 Amplif. : 100x Oscil. Tek. 555 3 8/11/73 22 7 161 500 20 Frequ. Counter tO for all Record- 4 8/12/73 15 15 135 500 20 ings - ( TABLE 2 Mieroeleetrode Amplifier: Input and Output Waveforms and Results Gain/em Photo Sine Sweep No. .fl. em In Out Input Res. 6 lK 2 msee 1 mV lV 500 7 lOK . 5 msec 1 mV lV 500 8 lOOK 1 mV lV 500 Gain/em Photo Square Sweep No. .JL em In Out Input Res. 9 lK 2 msec 1 mV lV 500 10 10K . 5 msee 1 mV lV 500 11 lOOK . 05 msec 1 mV 1V 500 ··- Gain/em Photo Square Sweep No. J1_ em In Out Input Res. 12 1K 2 msee 1 mV 1V 1 meghom 13 lOK . 5 msee 1 mV 1V 1 meghom 14 50K . 1 msee 1 mV lV 1 meghom • Gain/em Photo Sine Sweep No. Jl em In Out Input Res. 15 1K 2 msee 1 mV lV 1 meghom 16 10K . 5 msec 1 mV lV 1 meghom 17 50K . 1 msee 1 mV lV 1 meghom 10 Fig. 7. Microelectrode amplifier input and output This document page appears to be a table of contents or index for a research paper, listing numbered entries with corresponding titles and page numbers. The titles primarily relate to microelectrodes, amplifiers, electroreceptors, and fish anatomy, specifically mentioning "Gnathonemus petersii." There are no photographs, diagrams, stamps, handwritten annotations, signatures, or filled-in forms visible on this page. The page is primarily text-based, organized in columns of numbers and corresponding descriptions. meghom • Gain/em Photo Sine Sweep No. Jl em In Out Input Res. 15 1K 2 msee 1 mV lV 1 meghom 16 10K . 5 msec 1 mV lV 1 meghom 17 50K . 1 msee 1 mV lV 1 meghom 10 Fig. 7. Microelectrode amplifier input and output waveform and gain (see Table 2). Fig. 8. Microelcctrode amplifier input and output waveform and gain (sec Table 2). 11 Fig. 9. Microelectrode amplifier input and output waveform and gain (see Table 2). Fig. 10. Microclcctrodc amplifier imput and output waveform and gain (sec Table 2). 12 Fig. 11. Microelectrode amplifier input and output waveform and gain (see Table 2). Fig. 12. Microelcctrodc amplifier input and output waveform and gain (see Table 2). 13 Fig. 13. Microelectrode amplifier input and output waveform and gain (see Table 2). Fig. 14. Microelcctrode amplifier input and output wa vcf orm and gain (see Table 2). 14 .. ·:·)-'-';·-~~~---~-·-, _,._""'!:~-- ..,.4, ..... _.~...-~-----------_,....--~------,----- .,.._.., Fig. 15. Microelectrode amplifier input and output waveform and gain (see Table 2). Fig. 16. Microelcctrode arnplificr input and output waveform and gain (sec Table 2). 15 Fig. 17. Microelectrode amplifier input and output waveform and gain (see Table 2). Fi~. 18. Microclcctrodc amplifier input and output waveform and gain. 16 '- For electric receptors we found two types of mormyromasts (A and B) and one type of tuberous organ. They are confined to well defined areas of the epidermis. The epidermis of these regions has a particular structw·e, which is developed in the Gymnotoides in a simiL'lr way. Its es sential components are columns of very thin, flat hexagonal cells 60 p.m in diameter, invariable in an species and body sizes. The height of the columns depends on location, but increases with body length. The mormyromasts are not covered by the hexagonal cells, but by small polyhedric cells which are arranged in a circular pattern. The A-type mormyromasts possess an opening toward the surface and are evenly distributed with a relatively wide space between them. The B type mormyromasts have no opening to the surface, and are more numerous than the A-type and are also evenly distributed. The tuberous organs lack an open connection to the surface and form distinct patterns (Fig. 19). They can be classified according to the number of their giant sensory cells (1 to 10). All mormyromasts and tuberous organs are innervated by lateral line This page is from a declassified CIA document, likely a report or log related to the MKUltra program, given the context of the collection. It displays a list of numbered items, each with a corresponding textual description and a page number to the right. These descriptions appear to be captions for figures or experiments, detailing scientific apparatus and procedures. There are no photographs, handwritten annotations, stamps, forms, diagrams, tables, or redactions visible on the page. The layout suggests a structured report format, with a "Figure" heading on the left and "Page" on the right. than the A-type and are also evenly distributed. The tuberous organs lack an open connection to the surface and form distinct patterns (Fig. 19). They can be classified according to the number of their giant sensory cells (1 to 10). All mormyromasts and tuberous organs are innervated by lateral line nerves. Only the tip of the chin with its Lorenzini ampullae is innervated by the Nerve trigeminus. Each mormyromast is enclosed by a loop of capillaries. The common lateral line system has developed only along the trunk and the tail. In the head only deep laying canals exist, but without sensory cells. The tuberous organs are characterized by an autorhytmic activity yielding a few m V, and with a high repetition frequency exceeding 1 kHz. The duration of the spikes are approximately 300 p.sec. The transmitting electric organ of Gnathonemus petersii is located in the tailstalk, occupying 2/3 's of it and represents approximate 12% of the total length of the fish. 17 \ \ \ I l ,--~-" ! l ! / ! I ' I i ! ) I f { A Fig. 19. Tuberous organ (electroreceptor) of Gnathonemus petersii. 18 The repetition rate of the impulses are influenced by light. In day light the rest repetition rate is between 7 and 10, in the night it increases to 15-20. It will also increase considerably in the case of a stimulus affect ing the fish. The EMF of the fish with no load and out of water is between 7 and 17 volts depending on the particular specimen. The internal resistance is around a few kilo-ohms. The electroreceptors sensory fields of Gnathonemus petersii can be clearly visualized if we put the fish in a solution of 10% buffered formaline. Figure 20 and 21 show the limits of these sensory fields. There are between 700 and 1000 tuberous organ electroreceptors, between 800 and 1000 type A mormyromasts electroreceptors and between 2100 and 2300 type B mormyromasts electroreceptors in the skin of an adult Gnathonemus petersii. The total number of electroreceptors varies between 3600 and 4300. These are distributed on the body as follows: between 42 to 46% on the head on 41 to 44% of the electroreceptor fields; between 30 and 32% on the dorsal sides on 27 to 30% of the electroreceptor fields; and between 22 and 26% on the ventral sides qn 25 to 32% of the The image displays a page of text with a heading "1. INTRODUCTION". The text discusses research on mormyrid electric fishes and their electroreceptors, specifically mentioning the "Lorenzini ampulla". There are no photographs, handwritten annotations, stamps, forms, diagrams, tables, or redactions visible on this page. The page number "1" is present at the bottom. The image contains a page of text with a numbered section heading: "2. METHODS AND INSTRUMENTATION". The text discusses experimental procedures involving electric fish, lucite trays, and microelectrode amplifiers. There is no visible imagery in the form of photographs, diagrams, or schematics. There are no handwritten annotations, signatures, or official stamps. The content suggests a scientific or technical report detailing experimental methods. the body as follows: between 42 to 46% on the head on 41 to 44% of the electroreceptor fields; between 30 and 32% on the dorsal sides on 27 to 30% of the electroreceptor fields; and between 22 and 26% on the ventral sides qn 25 to 32% of the electroreceptor fields. The total area of the electroreceptor fields may occupy between 2000 and 2 5000 mm area for fishes between 90 and 125 mm length. Figure 22 shows the different types of mormyromast electroreceptors of Gnathonemus petersii. With the exception of the sensory receptors of the chin which are mech anical displacement receptors and are connected to the CNS through the Nervus trigeminus, the mormyromast electroreceptors are subserved by the lateral line nerves. Figure 23 shows the main branches of the lateralis nerves system. All the mormyromasts types (tuberous, A and B) are connected to nerves forming bundles pertaining to the lateral line system and ending in the brain. 19 -----------------------------~---------- -- Fig. 20. The electric sensory fields of Gnathonc mus petersii. Fig. 21. Limits of the electrorcccptors sensory fields of Gnathonemus petcrsii. 20 -. ·-------~----- -·------ -------~·--.~·~--------------- -------------------·- ... ----·--·---------------------------- . ,n.nl .~J ~ ir)_() - [ij ~ )\ '1/ '-?' ~) -,/ ...' \..1 • 1 1.11 ~. _... - r~ :· :_~)} b ~;.--.. :::;;::;:/ a Fig. 22. Different types of mormyromasts: a. tuberous organ b. A-mormyromast c. B-mormyromast (top and ·cut view). 21 • --~ • .._. .. 7".0'1_. ...... _.,_~----- ... ---~----...-. ------~-___ ......... __ _..._. ........- -... ·--~·..----~---·----·---..... ....-. .... -·-·------..... --------.. - ..,...... ~----,--~ ,_,..~ ··-·.-..-- - ..... ..... Cfl M ..Q...). Qc). Cfl :a:I Q) ~ 0 ..c: d ~ l? -..c: ..C..f.l ..t.J.. ..M.... - tJ Q) Q) -.. Q c ) : ...... 0 rn Q) > M ~ - -Q) ..... ~ ro M .-.Q...). ro . ..t..n. ~ 22 The tuberous or{.;.m clectroreccplors arc autorythmic and the EMF may reach a few millivolts. The repetition rate varies from 550 to 3!>00 with the most often encountered repetition rate between 0. !>5 and 1. !>5 kHz. Figure 24 shows a comparison between sensitivity and density of the electroreceptors in the epidermis of Gnathonemus petersii and Fig. 25 shows the autorhytmic activity of the electroreccptors ncar the chin and ncar the eye. Figure 26 shows the autorhytmic activity of the mechanical displace ment sensory organs as an effect of The document contains two black and white line drawings. The top drawing, labeled "Fig. 1," depicts a fish with a long, pointed snout and a distinct tail fin. The caption identifies it as an "African fresh water weakly electric fish Gnathonemus petersii." Below this, "Fig. 2" shows a similar fish placed within a rectangular tray designed with multiple vertical bars, which the caption describes as a "restraining tray provided with stainless steel electrodes." A solitary number "3" appears at the bottom center of the page, likely a page number. There is no visible evidence of official stamps, handwritten annotations, or redactions on this page. shows a comparison between sensitivity and density of the electroreceptors in the epidermis of Gnathonemus petersii and Fig. 25 shows the autorhytmic activity of the electroreccptors ncar the chin and ncar the eye. Figure 26 shows the autorhytmic activity of the mechanical displace ment sensory organs as an effect of bending the proboscis of the chin. Experiments in this direction would be continued to record wave form and changes in repetition rate as a result of different stimuli. 23 -r----- . ·---- --r u--~- 1 . ! I . i ; ' ~ : ,: . ------+-~----+~----4------ I.C Fig. 24. Comparison between sensitivity and density of the electroreceptors of Gnathonemus petersii in the epidermis. c Fig. 25. Autorhytmic activity of the electroreceptors of Gnathonemus petersii: a. 500 Hz calibration signal b. electroreceptors near the chin c. electroreceptors near the eye 24 i j j l .:: 1 . 1 ' -,~ i I a .................................................. i ~-------------·························································-···· I ~ { b il :•j,!.;J;JJ.i.illJilJ!JiJjJ.IJlJ.;~j~;;!JjJJJ)]jjJ:)lJtU.lJJ.!JliiJJJUJJlliJJJ.Jh'IJJJ!~JIJIIJJJUlJIJJJllljltJ IIIJJIIJJJJIIIJ !jiJJ_:jJJ! I :_:_tl: I:' I:' ''fjlllll I! • Ct.::. .. -w---.. ... .,_.., ... _;;..,_,...~.,...__-...... 1;;'"'J". ......... --· ... ~-.~ .. ~·---........................ !!:a! .... ~ .. ~. . ~~:t..': ....... ~~:r:!:! •• ~~.~~.JZt...~ ~ l l c j ') l i I a I ! I ; b c v!" l i ' ; .. . .. ' . . .. l .. J ... J .. J .. J ..,. J ... j :; j l' i ,.. j ,. j .. . v1r!. .I,J•· · ! - J .. J .- "IJ• J..J...J...J..J. ,.. J .;;.; ;.1 I .: J .. J . ., L .... !J __ J . ., J .., . . j . _ ... j : r-.1. ~ I . J . ~ l j .. j . _ ' J - ll " ~~ ..,..._ _ .., _.. IJ ~ . , J ¥ .I . J , .+ : i ' j l .: ' . ' . J 4 I J I , i ~ i K l · j ..j.'. U'. ~,.J,.l .J..J ~ lij ..J : I r J \ i , ' . . . : ? ~ ' · . :· . · . ., ' . : . : . • , : ~ ., . ~ , : v : ~ ! ~ 1 ~ ~ CJ1 Fig. 26. Electric ..J : I r J \ i , ' . . . : ? ~ ' · . :· . · . ., ' . : . : . • , : ~ ., . ~ , : v : ~ ! ~ 1 ~ ~ CJ1 Fig. 26. Electric activity from the nervus lateral anterior innervating receptor near the proboscis of a mechanical displacement on the chin of Gnathonemus petersii when the proboscis has been moved upwards. = a. time marks 50 Hz b. electric activity in the nerve c. movement of the chin proboscis 4. LARGE WATER TANK PREPARATION FOR EXPERIMENTS The 12 ft. diameter, 4 ft high water tank has been prepared for the other experiments that will follow for the Phase II investigation (Fig. 26). Heating the water is done with 2 x 1000 watts heaters controlled by ± an "YSI" temperature controller to .1 °C and is normally held at 25°C. The heaters are in a separate 30 gallon tank and are connected to a relay switching them on and off and controlled by the temperature controller. Two 9 gallon per minute pumps are pumping in and out the water from the 30 gallon tank from and into the large tank (Fig. 27). Rails with nylon strings are provided for the silver -silver chloride platinized-silver-chlorized electrodes which can be moved from one end to the other end of the tank (Fig. 28). The electrodes are connected to are mote controlled differential amplifier (ampl. fact. x 4200) suspended over the. tank and from the amplifier to the differential oscilloscope Tektronix type 555 (Figs. 29, 30 and 31). An electric fish can be suspended in one of the restraining devices shown in Fig. 32. The fish restraining devices are provided with stainless steelend electrodes which are connected to an audio-amplifier (ampl. fact. = 300) and to the oscilloscope and displayed on a second beam. Our preliminary experiments show good promise for recording the changes in the field of electric fishes produced by them as a result of stimuli they are presented with. 26 ·- ' . . '· --... , ... Fig. 27. 12 ft. diameter fiberglass tank provided with heating, filtering, countercurrent aeration and double rails for electrode support. Heating tank provided with automatic Fip;. 28. control of temperature to 0. Ol°C. 27 ,_ Fig. 29. Differential amplifier hanging over the water tank . • ._. The page contains a paragraph of text describing amplifiers for electroreceptors. There are no photographs, handwritten annotations, official stamps, forms, diagrams, schematics, tables, or redations visible on this page. The text refers to figures 3, 4, 5, and 6, which are not present on this page, suggesting they are likely elsewhere in the document. A page number "4" is visible at the bottom center of the page. The document