PATHOLOGY OF SENSIBILITY 31 



functions of gnostic sensibility. Astereognosis especially 

 is frequently seen in such cases. 



Clinical and anatomical studies have given me the con- 

 viction that the same division into two pathways is present 

 in the sensibility of the head, conducted by the trigeminal 

 nerve. The so-called spinal root of the fifth nerve is the 

 homologon of the gray substance of the posterior horn. 

 Here stimuli are conducted for pain, heat and cold and a 

 part of those for touch. The other sensory functions are led 

 by the frontal trigeminal nucleus, which is the homologon of 

 the nuclei of GoU and Burdach. From these centres also 

 two different pathways proceed in the direction of the 

 optic thalamus and of the cortex. 



The fact that several investigators regarded the sensory 

 functions of the posterior columns as a higher form of sen- 

 sibility, has led me to make a study of the development of 

 these sensory systems in the scale of evolution. In the 

 Central Institute for Brain Research I studied sections of the 

 spinal cord, stained after Weigert-Pal, van Gieson and with 

 Carmine, of the following animals. 



Fishes: Chimaera, Amia calva, Acipenser sturio, Rhombus maximus, 

 Silurus glanis, Lophius boudegassa. 



Amphibians: Rana, Siren lacertina. 



Reptiles: Python, Lacerta, Varanus, Chamaeleon, Chelone mydas. 



Birds: Ciconia alba, Spheniscus demersus, Colymbus septentrionalis, 

 Casuaris. 



Mammals: Homo, Cebus, Leontopithecus rosalia, Callitrix, Simla 

 Satyrus, Hylobates, Cedipomidas, Felis, Canis familiaris, Heli- 

 arctos malayanus, Putorius putori. Bos taurus, Hippotragus niger, 

 Elephas, Tragulus javanicus, Lepus, Dasyprocta, Phocaena, 

 Sorex, Talpa, Macropus, Tamandua, Didelphys marsupialis. 



The first cervical segment of these animals was measured 

 and the relation between the size of the posterior columns 

 and of the remaining part of the white substance was deter- 

 mined. For details I refer to my article formerly published. 



The principal results w^ere the following. 



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