106 



MATHILDE L. KOCH AND OSCAR RIDDLE 



this table. These show that (from the standpoint of relative 

 amounts of the various chemical constituents) the cerebellum- 

 medulla of the pigeon is chemically an intermediate of the pigeon 

 cerebrum and the human brain (both of cerebrum and of cere- 

 bellum-medulla). Only the sulphatids of the seven fractions 

 from the pigeon cerebellum-medulla fail to take an intermedi- 

 ate place between the pigeon cerebrum and human cerebrum. 



TABLE 9 

 Comparison of the chemical corn-position of the adult cerebrum and cerebellum- 

 medulla of man and of the pigeon (in per cent of solids) 



CERE- 

 BBO- 

 SIDEB 



(Part 1) 

 Cerebrum 



(Part 2) 

 Rearrangement of above figures in terms of decreasing (ontogenetic) age 



Human cerebrum.. 

 Human cerebellum. 

 Pigeon cerebellum. 

 Pigeon cerebrum... 



6.6 



7.4 



1 Average of two analyses by Koch and Voegtlin ('16) of cerebrum and cere- 

 bellum-medulla. 



2 Average of two analyses (I-Ia and II-IIa of this paper). 



3 Cerebrosides have not been determined in the pigeon brain. 



If, now, the figures found in part 1 of table 9 be arranged in 

 such an 'age series' as was prepared for the several pigeon brains of 

 various ages (table 8), the result may be seen in part 2 of table 9. 

 According to the places taken by cerebrum and cerebellum- 

 medulla of man and the pigeon in this arrangement, the human 

 cerebrum would seem to be the oldest — i.e., the most fully differ- 

 entiated 'brain tissue;' the human cerebellum-medulla nex. in 

 order; the pigeon cerebellum-medulla next. The pigeon cere- 



