IV 



PATTERN ADAPTATION OF FISHES AND THE MECHAN- 

 ISM OF VISION^ 



The mechanism of the action of the brain is entirely 

 unknown to us. We are unable to look into the active brain 

 and the objective results of brain action are in general so differ- 

 ent in their nature from the external stimulus which leads to the 

 action that we are prevented in most cases from drawing any 

 conclusions concerning the nature of the processes occurring 

 in the brain. 



From results obtained in experiments on dogs Munk stated 

 years ago that there existed a projection of the retina on a part 

 of the cortex which he had designated as the visual sphere and 

 that the extirpation of definite parts of this sphere caused 

 blindness in definite parts of the retina. I repeated these 

 experiments but was not able to confirm his statements. 

 Henschen has recently, however, furnished the proof, on the 

 basis of excellent pathological observations on man, that such 

 a projection after all exists, but that it is situated in another 

 part of the cortex from where Munk had believed it to be, 

 namely, in the area striata. Minkowski was able to confirm 

 Henschen's conclusions through experi lents on dogs. These 

 observations and experiments suggest the possibility that in 

 vision an image is formed not only on the retina but also on the 

 cortex. 



The possibility that vision is based on the formation of an 

 image in the brain is supported by a group of facts which to 

 my knowledge have never received any consideration in this 

 connection. 



1 Reprinted from Physiologisches Centralblatt, XXV, No. 22, 1912. This 

 note is given merely as a suggestion concerning the mechanism underlying certain 

 brain processes. 



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