Stroud, Mammalian Cerebellum. 83 



and that it should always be followed if we expect to gain an 

 intelligent knowledge of the brain as a whole or in part. 



So far as we can judge from the study of two forms so 

 widely separated as are man and the cat, it seems prob- 

 able that the general structural plan is the same for all mam- 

 mals. The question then arises, what is the difference between 

 man's cerebellum and that of other mammals ? 



If one had specimens from the whole mammalian series 

 placed before him, it is true the first impression would be that 

 there was little resemblance between them, least of all to man's. 

 A closer study and analysis discloses many features which do 

 appear to be homologous. And I can positively say that so far 

 as the embryos of cat and man are concerned the early stages are 

 apparently identical. The same features and regions are present 

 Both start from the same point; soon, however, modifications 

 appear and the two rapidly diverge from each other. But in 

 spite of all this, embryonic regions, whether they become al- 

 most obliterated or hypertrophied beyond all proportion, do 

 persist throughout the life of the individual. 



But to return to the question, how does man's cerebellum 

 differ from the others ? I hold that it is simply a case of differ- 

 ence in degree of developnumt. 



Intrinsic Terminology. — Unfortunately we possess no intrinsic 

 terminology of the cerebellum. What effort has already been 

 made in that direction is mostly of a superficial and artificial 

 character. The thing needed is a terminology which shall ap- 

 ply equally well to the cerebellum of an opossum, a sheep, or 

 man. Until this has been done, the cerebellums of different 

 mammals can not be easily compared. 



The introduction of new terms, while undesirable, is a ne- 

 cessity, because the present terminology is inadequate. 

 There are distinct regions which, it is believed, have never be- 

 fore been recognized. Wherever new terms occur they will be 

 explained. In all possible cases terms already familiar have 

 been retained. 



It seems to me that terms applied to parts of the cere- 

 bellum ought not to be applied to structures of the cerebrum ; 



