286 C. CLIFFORD DOBELL. 
Chromidia were first found in Pelomyxa by Goldschmidt 
(05). His discovery was confirmed by Bott (’06), who 
agreed that they were products of the nucleus, like those of 
Actinospherium. They are produced when the animal 
hungers. But Bott was able to show further that chromidia 
play an important role in sexual reproduction. Al] the 
nuclei fragment, forming ‘‘ somato-generative chromidia,”’ 
of which a part degenerates and is cast out. The rest increase 
in size and form new nuclei, which—after eliminating more 
chromatin in the form of chromidia, and undergoing certain 
changes—give rise to gamete nuclei. Thus, in. its essential 
points, gametogenesis in this creature resembles that of 
Entameeba coli. 
Chromidia have been described in Amceba proteus by 
Calkins (705). ‘The nucleus was said to divide by mitosis, 
until, after repeated division, a multinucleate condition of the 
cell resulted. ‘These ‘primary nuclei” then broke up into 
“secondary nuclei” (by chromidia formation), and the 
“secondary nuclei” divided to form the hypothetical gamete 
nuclei. Since publishing this description Calkins has re- 
investigated the same material upon which these ‘“ evidences 
of a sexual cycle” were based. He now (Calkins, ?07) comes 
to a quite different interpretation, and claims to have dis- 
covered the “fertilisation” of Amceba. The “ secondary 
nuclei’ are now said not to divide, but to fuse in pairs—thus 
undergoing a kind of autogamy. I do not wish to enter into 
a long discussion of this matter, but I must point out—as the 
fate of the chromidia bears upon the present subject—that 
Calkins’ account is, by his own showing, impossible to accept. 
Apart from the fact that the whole story is based upon only a 
few preserved specimens, there are serious discrepancies in 
' The “ mitosis,” as far as one can judge from Calkins’ figures, is 
quite unlike mitosis as usually understood. Awerinzew, moreover, has 
described and figured in detail the mitosis of this organism. Judging 
from my own impressions and from Awerinzew’s description, I am 
inclined to believe that Calkins’ figures do not represent division stages 
at all. 
