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H. E. Jordan 
acid. Alcohol, etlier, and Chloroform may alter the mitochondria but 
do not destroy tliem. Chemically lie regards them as consisting of an 
albuminous substratum which contains lipoid bodies. They are also 
supposed to be separated from the more fluid hyaloplasm by a lipoid 
pellicle. Faure-Fremiet studied also the germ-cells of certain insects 
(Pyrrhocoris, Forficula, Apis, etc.) and reports that their mitochondria 
are also insoluble in acetone, alcohol, ether and Chloroform. But after 
the action of these solvents for fat, their affinity for osmic acid is consider- 
ably diminished (p. 165) and certain color reactions no longer result as 
readily or at all. He concludes that only the combination into which 
the fatty acids enter present all the histochemical cliaracteristics of mito- 
chondria. Regaud also classifies the mitochondria in the seminal epithe- 
lium of the rat among the hpoids or hpoproteids but describes them as 
soluble in alcohol. Likewise Nageotte was unable to detect mitochondria 
in nerve cells after treatment with alcohol. 
To return to the question and theories of origin: The theory of 
mitochondrial continuity proposed by Altmann, Benda and Meves. 
and developed by the latter and by Duesberg, is very attractive; 
and it appears to rest upon considerable cytological evidence. On the 
other hand, the nuclear origin of chromidia (which structures, in 
common with most workers in the field, I shall consider identical with 
mitocliondiia) seems equally well supported by equally forceful cyto- 
logical evidence. 
It remains to describe and interpret c-onditions in the opossum with 
respect to the chromidia (mitochondria) in the light of the two opposing 
tlieories above outlined. As already stated, the evidence in the opossum 
points directly to a nuclear origin of the mitochondria. Before detailing 
tliis evidence, however, it seems best briefly to consider Duesberg's 
objections to the evidence offered by several workers in support of tliis 
view, notably Goldschmidt (1904 — 1909), IYassilieff (1909), Popoff 
(1909) and Büchner (1907). 
A number of workers have noted the appearance of mitochondria 
during the growtli period of the primary spermatocyte. Thus Mont- 
gomery (1910) in Euchistus (he subscribes to a nuclear origin here); 
Morse (1909) in Blatta germanica-, Büchner (1907) in Oedipoda, Gryllus 
and other orthoptera, where he believes that the accessorv eliromosome 
contributes to the formation of the mitochondria; and Wassilieff (1907) 
in Blaps. The latter investigator describes an expulsion of the nuclear 
material in the primary spermatocyte upon which the formation of 
the mitochondria is supposed to depend. He also recognizes a small 
