George L. Streeter 343 
tion in all stages, from simple folding of the brain wall up to conversion 
of the entire central nervous system into a pulpy mass. Evidently cortical 
papille and transitory fissures, though differing in character, have a sim- 
ilar etiology; as in the above experiment we have both, artificially pro- 
duced in the same brain under known conditions. The interesting fact 
should be noted that though the two formations may occur in the same 
brain, and may closely adjoin each other, yet they do not occur together 
at the same place; that is to say, one does not find a fungiform grouping 
Hie. 5. Hig. 6. 
Fic. 5. Section of the brain of a pig embryo, 11.5 cm. long. The embryo 
was left exposed to the air, and the brain allowed to macerate in its own 
fluid 48 hours. The brain was then removed and preserved in formalin fol- 
lowed by Miiller’s solution. In this section the fungiform clumping involves 
cnly the outer part of the pyramidal zone, and in this respect closely 
resembles the condition seen in Fig. 1. 
Fic. 6. Section of same specimen shown in Fig. 4. The maceration here 
is more advanced than that seen in Fig. 5. The fungiform clumping involves 
the whole thickness of the pyramidal zone, both the inner and outer surfaces 
of which are thrown into coarse irregular folds. 
of the cells that lie in the cleft of a transitory fissure. Hither process 
seems sufficient to satisfy the space demand. 
Sections from the specimen macerated in its own fluids (B2), see Fig. 5, 
differ from those macerated directly in salt solution in that the fungiform 
arrangement of the cortical cells involves only the more superficial part 
of the pyramidal layer. Instead of foldings of the whole layer, such as 
is seen in Fig. 6, we have here only a granulated or fungiform surface ; 
and this duplicates almost exactly the condition found in the embryo Pl 
