234 



ANATOMY OF THE CENTEAL NERVOUS SYSTEM. 



Spitzka, and others. For recent compilations, criticisms, and comparisons, we are 

 especially indebted to Turner, then to Ziehen and Kiikenthal. The numerous varia- 

 tions from the type described, whether they may exist normally or on account of 

 malformations, have received consideration from most of the above-mentioned au- 

 thors, but particularly from Richter, Sernoio, and others. 



For the olfactory apparatus, the older investigations of Meynert, Ganser, Bevan 

 Lewis, and others, are the foremost. The description given in the text follows per- 

 sonal investigations made in common with Dr. Flatow. More recent important re- 

 searches come from Kolliker and from Loicen.thal ("degeneration" experiments). 

 Finally it must be emphasized at this point that, as the excellent investigations of 

 Elliott Smith show, the brains of the marsupials and the monotremes present espe- 

 cially clear and simple relations for the central olfactory apparatus. 



A perusal of the work of this investigator is particularly recommended. 



It does not lie within the scope of this text-book to impart the rich store of 



Fig. 148. — The projection areas of the cortex at present known. 



facts concerning the functions of the separate parts of the brain ^^'hich pathology has 

 ascertained. The study of the function of the cerebral cortex is still entirely in its 

 infancy, and is in nowise concluded. It may be said, in general, that more is posi- 

 tively known about man than about animals concerning the phenomena occurring 

 after injury to the cortex. The following comprehends a short summary only of 

 these symptoms: — 



Injuries that involve the normal structure and the normal function of the cere- 

 bral cortex produce, in man, different symptoms, according to the place where they 

 are located. Up to the present time, several hundred carefully observed cases of 

 disease of the cerebral cortex have been known, and, bj' comparing .these with one 

 another, the following conclusions may be arrived at: — 



Motor symptoms of irritation (from the twitching of a single muscle up to 

 epilepsy) may arise from any point of the cerebral cortex. There exists a zone of 



