Stroud, Mammalian Cerebellum. 107 



J^igs. 77, iS, ig. Cerebellum of an embryo kitten 77 mm. long, No. 3443 



(x7.5)- 



Fig, ij. Shows the dorsal aspect. The organ presents numerous folia and 

 begins to assume distinctly adult characters. At this stage the vermis may be 

 recognized but it still presents a mesal depression. Upon each side there is a 

 rather wide depression which becomes the vallecula of the adult. The brain 

 was somewhat distorted in hardening ; this is an advantage because it allows 

 the left flocculus and paraflocculus to be seen from the dorsal aspect. A de- 

 pression is seen in the paraflocculus, the interfloccular sulcus. It divides the 

 paraflocculus into two parts, of which at Professor Wilder's suggestion, I have 

 called the dorsal part, supraflocculus, and the ventral part, mediflocculus. 



The flocculus proper is not diff"erentiated as early as the paraflocculus. 

 This is the youngest specimen that shows it clearly. The early embryos show 

 an apparent connection between the supraflocculus and the postpileum. The 

 same condition exists in the adult but is obscured by the great development of 

 the adjacent parts. An attempt will be made in Part II to trace the fiber rela- 

 tions of these two regions. A connection also exists between the floccular re- 

 gion (flocculus and paraflocculus) and the postvermis. I get this idea from dis- 

 sections of adult cerebellums. This connection is indicated by the term ver- 

 mian tract. 



A considerable portion of the preramus and its middle part, the prevermis, 

 is seen, also the relations of the furcal sulcus and the peduncular sulcus, next 

 caudad. The entire mass from the peduncular sulcus caudad to the uvular 

 sulcus represents the cacumen and the tuber. The cacumen in the cat is rela- 

 tively much larger than in man. The remaining part of the postvermis, shown 

 in the figure, represents the uvula. The pyramis is rudimentary in the cat. See 

 Fig. 44, PI. IV, The floccular and nodular sulci do not appear in this aspect. 



Fig. 18. Right lateral aspect of the same specimen ; the right aspect was 

 drawn because the left was distorted. In additition to the general features it 

 shows the lateral U-bend and its relation to the parepicoele, the auditory region, 

 and the auditory nerve. 



Fig. ig. Shows an oblique view of the same specimen (x ii-5). Shows the 

 relation of the supraflocculus to the postpileum, also that of the flocculus and 

 paraflocculus to postvermis, by means of the vermian tract. The other parts 

 need no explanation. 



Figs. 20,21, 22. Cerebellum of an embryo kitten 93 mm. long, No, 3344, 

 (x about 6.7). This specimen shows all the features of the adult organ but in a. 

 much more simple condition. The individual regions do not show that crowd- 

 ing together and distortion which in the adult organ are so puzzling. From 

 now on the growth appears to be an elevation of the general surface, not in- 

 cluding the primary sulci. 



The vermis presents no mesal depression, but instead a mesal elevation. 

 All the mesal parts present in the adult may now be recognized. The postpileum 

 has undergone an enormous change, both in relative size and in general appear- 

 ance. Its long axis has changed to a latero-cephalic direction; it has also been 

 crowded dorso-caudo-mesad so that it has come to lie up against the postvermis, 

 and now is much thicker than wide. The nodulis is concealed by the uvula. 



