CENTRAL NERVOUS SYSTEM. 705 



From the experimental work of the strict localizationists like Hitzig, 1 

 Munk, 2 and Ferrier, 3 and from the work of those who, like Goltz 4 and Loeb, 5 

 denied a strict localization in the cerebral hemispheres, several important points 

 of view have been developed. 



In the first instance, anatomy indicates that in the central system there are 

 but few localities which consist only of one set of cell-bodies, together with 

 the fibres coming to these bodies and going from them. Almost every part 

 has both more than one set of connections with other parts and also fibres 

 passing through it or by way of it to other localities. Hence in removing any 

 part of the hemispheres, for instance, not only are groups of cell-bodies taken 

 away, but a number of extra pathways are interrupted at the same time, and 

 thus the damage extends beyond the limits of the part removed. Moreover, 

 when any portion of the central system has been removed there is a greater or 

 less amount of disturbance of function following immediately after the opera- 

 tion ; but this disturbance partially passes away. There are thus " temporary " 

 as contrasted with " permanent " effects of the lesion, and these require to be 

 sharply distinguished, because it is the permanent loss which is alone sig- 

 nificant in these experiments. Finally, it has been made clear that neither the 

 relative nor the absolute value of any division of the central system is fixed, 

 but depends on the degree to which cephalization has progressed, or, to use the 

 more common measure, the grade of the animal in the zoological series, both 

 expressions signifying an increase in the connections between the cerebrum 



FIG. 199. Schema of the encephalon of a bony fish embryonic (Edinger). The vertical black line 

 marks off the structures in front of the thalamus. 



and the lower centres. The age of the animal on which the operation has 

 been made is also of no small importance in this respect. These relations 

 can be illustrated by reference to several experiments. 



Removal of Cerebral Hemispheres. If from a bony fish the cerebral 



1 Untersuchungen uber das Gehirn, Berlin, 1874. 



2 Ueber die Functionen der Grosshirnrinde, Berlin, 1881. 



3 The Functions of the Brain, London, 1876. 



4 Ueber die Verrichtungen des Grosshirns, Bonn, 1881. 



5 Arch, fur die gesammte Physiologie, Bde. 33 u. 34, 1884. 

 45 



