LoESER, Fimctions of the Frogs Brain. 363 



Opposed to my observations are those of Steiner^ who 

 states that the frog deprived of the cerebrum does not take 

 nourishment spontaneously or carry on willed movements, and 

 that the region presiding over these functions is in the posterior 

 portion of the cerebrum. 



The operations on the optic thalami indicate that these, 

 more than any other portion of the frog's brain contain the pri- 

 mary nuclei of the nervus opticus, and that this nerve joins their 

 ventral, rather than their dorsal portions. The permanent re- 

 duction of voluntary movements and tactile sensibility noted 

 after excision of these bodies may be regarded as an important 

 deficiency phenomenon, and I assume that the principal reflex 

 ganglion of the sense of touch is located in these bodies. The re- 

 duction in voluntary movements must be attributed more to the 

 presence of a motor nucleus in these bodies than to a destruction 

 of associative connections which they have with other motor 

 ganglia, for this phenomenon lasted during two and a half 

 months. 



My results and conclusions in regard to the optic thalami 

 strengthen those obtained by Schrader" who states that frogs 

 deprived of the optic thalami show a decrease in voluntary move- 

 ments and sensitiveness to touch and complete blindness. My 

 observations and conclusions do not agree with those of Steiner 

 who admits that there seem to be primary elements of sight in 

 the optic thalami of the lizard, but show instead that this is con- 

 trary to what is found in the frog; and they do not agree with 

 the results of Sellier and Verger'^ who found that in the dog 

 injury to the optic thalami causes transient disturbances of the 

 muscular and touch sensibility. 



The operations on the optic lobe showed that the anterio- 

 ventral quarters of these bodies are in close association with the 

 retinal part of the optic thalami, but that the chief center of the 



^ Steiner. Die Functionen des Central Nervensystems und ihre Phyloge- 

 nese, Abtheilung 4. 



2 ScHRADER, M. PJiuger's Archiv, 41, 75, 1887. 



^ Sellier and Verger. H. C. R. Sodetes de Biologie, Mai, 522, 1898. 



