302 C. CLIFFORD DOBELL. 
stain (with iron-hematoxylin or brasilin) just like the nuclear 
chromatin. 
The increase of chromidia with increased activity is thus 
explained : the more prolonged and violent the stimulus, the 
greater the damaging and tearing of the fibrils, and hence the 
greater the number of ‘* chromidia.”’ 
Whether Goldschmidt or Vejdovsky ultimately prove to be 
correct, it is important to note for the present that the 
“ chromidia” of Ascaris may be really nothing more than 
much modified derivatives of centroplasmic rays (cf. p. 303). 
The Chromidia in the Gametogenesis of Gastro- 
pods.—The advocate for chromidia in the development of 
gastropod! eges and sperms is Popoff. According to him 
(07) chromidia are formed in the spermatocytes and oocytes 
at certain stages of development (cf. text-fig. 20a). They are 
extruded from the nucleus as chromatin granules. Personally 
I am far from being convinced of the nuclear origin of the 
p) 
“chromidia,” either by his figures or his description. 
Now the “chromidia” are really nothing more than the 
““pseudochromosomes,” “Nebenkern,” etc., already long 
known from the work of Meves, Platner, Bolles Lee and 
others (cf. Meves, 00). But for Popoff, “the observations 
(i. e. Popoff’s on Helix) . . . show that the structures 
described by various authors under the names mitochondria, 
pseudochromosomes, archoplasm, ergastoplasm, Nebenkern, 
idiozome (only in certain cases) and idiozome remains, are 
referable to different isolated stages of one and the same 
developmental series of the chromidia.’’ He considers his 
work to be an “undoubted proof” of this. 
Asa great deal has been written on this matter, U will 
content myself with citing the opinion of three other investi- 
gators of the same structures. 
Murray (98) found centrosomes in the Nebenkern of 
Helix. And he concluded that the Nebenkern was really 
the attraction sphere, and that in it “no structures exist in 
any way comparable to chromosomes.”  'l'his conclusion was 
1 Paludina and Helix. 
