THE PROJECTION OF THE RETINA IN THE 



BRAIN 



The subject of my first Herter lecture is the projection of 

 the retina in the brain. Several of your scientific workers 

 in America have given much thought to this problem. 

 I refer, for example, to the studies of Adolf Meyer, Gushing 

 and G. E. de Schweinitz. I like very much to speak on this 

 subject, because this problem has attracted me very much 

 for several years. There is however one difficulty. I must 

 give my lecture in a language, which is not mine and which, 

 I fear, is also not yours. I have therefore brought a number 

 of plates and lanternshdes with me. They speak an inter- 

 national language and hence I hope you can understand me. 



To introduce you to the problem I have to remind you 

 that the experiences of the Great War have renewed our 

 interest in the cerebral organization of the optic pathways. 

 We have only to recall the careful investigations of Gordon 

 Holmes and Lister in England, of Pierre Marie and Chatelin 

 in France and of Axenfeld and others in Germany. 



The optic stimuli are caught by the retina, thus reaching 

 the layer of the ganglion cells. These cells send their fibres 

 into the brain, forming in the beginning the optic nerves. 

 These nerves, in lower animals, wholly cross. This is so in 

 fishes, amphibians, reptiles and in birds. It is also the case 

 in some groups of mammals. In these classes of vertebrates, 

 however, it is usually different. In rabbits, for instance, 

 some of the optic fibres do not cross, but remain on the same 

 side of the brain. In monkeys and also in men, as you 

 know, the number of non-crossing fibres is much larger. 

 Centuries ago Newton emphasised the fact that the optic 

 nerves in men only partially cross in the chiasma. This 

 was a theory he had deduced in his studyroom. His 



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