800 LIGHT AND LIFE 



The histology of the retina of a shallow water fish is shown in Fig. 

 2, together with a schematic drawing of the various cellular com- 

 ponents. A dye-marking technique showed the "L" response to ap- 

 pear in the outer plexiform layer in a region just below the synaptic 

 endings of the cones (17) . In fishes this region contains a large num- 

 ber of giant horizontal cells whose function is as yet unknown. It 

 is possible that the "L" responses are recorded from within these 

 elements. The chromatic responses were shown to arise at a depth 

 corresponding to the bodies of the bipolar cells in the inner nuclear 

 layer. They could presumably have arisen from within these cells. 

 However, Tomita (27) and Tasaki (26) have advanced persuasive 

 arguments that both the "L" and the "C" responses are extracellular 

 in origin. The situation is by no means clear, so that it is not yet 

 possible to settle the question. 



Whatever their origin may be, both the "C" and "L" responses are 

 localized and presumably are related in some way to the generation 

 of impulses in the ganglion cells. Since the axons of these cells 

 make up the optic nerve, their discharges constitute the visual in- 

 formation that is transmitted to the brain. Thus, if the intraretinal 

 responses have anything to do with color vision they must somehow 

 correlate with the patterns of discharge in the ganglion cells. There 

 were two preliminary requirements in selecting an experimental ani- 

 mal for studying this correlation. First, it should have demonstrable 

 color vision. Second, it should be possible to obtain a "C" response 

 as well as an "L" response and a ganglion cell discharge from its 

 retina. Recently, McCleary (18) has shown by an ingenious auto- 

 nomic conditioning technique that the goldfish (Carassius auratus) 

 appears to have a well-developed color sense. As will be shown later, 

 both "C" and "L" responses could be obtained from the retinas of 

 this species. Since the goldfish is universally obtainable and keeps 

 exceptionally well in the laboratory, it appeared to be an ideal ex- 

 perimental animal. Accordingly, the authors have undertaken an 

 experimental study of its retina. The following is a report of progress 

 in this program to date. The techniques and methods used in ac 

 complishing these studies were detailed in prior reports (32, 33) . 



Experimental Results 

 liotli the "L" and "C" responses have been recorded from the gold- 

 fish retina by means of micropipette electrodes. The responses were 

 qualitatively the same as those described by Svaetichin (24) . Fig. 3 

 shows a typical "C" response from the goldfish retina. So far we 



