The Spermatogenesis oi the Opossum (Didelphvs virginiana) etc. 
63 
in fecundation, i. e. that the chondriosomes of the embryonal cells are 
in part paternal and in part maternal. He and Duesberg (1910) have 
attempted to prove that in mammals the male mitochondria retain for 
a time their morphological individuality and contrast with, and are di- 
stinguishable among, the female mitochondria. He and Samssonow 
(1910) have made the Observation that the mitochondria are identical 
with the bioblasts of Altmann. In the fertilized egg of Ascaris, Meves 
Claims to be able to distinguish for a time the larger male mitochondria 
among the small female mitochondria. Both are regarded as carriers 
of heritable Anlagen. 
Rubaschkin (1910) notes that the primitive structure of mitochondria 
is granulär, the secondary or differentiated filar. In a study of the germ- 
cells of birds (chick), Tschaschin tries to show that this is a distinguishing 
characteristic between the primitive sex cells and the somatic cells. This 
can not be a universal distinction, however, since in many invertebrates 
and even in some vertebrates (e. g. ampliibia) the sex cells contain fila- 
mentous mitochondria. Tschaschin notes also that in his unstained 
preparations of FLEMMiNG-fixed material, the chondriosomes are not 
discernable, while the yolk granules are stained black. This reaction to 
osmic acid he employed as a differential characteristic between chon- 
driosomes and yolk granules. This may be true for his material, but it 
certainly is not universal! true (c. f. Regaud 1909, and Faure-Frsmiet 
1909). My own experience is absolutely contrary to this finding. Mito- 
chondria are very conspicuous (grayish-black) in the unstained Flem- 
MiNG-fixed material of the Opossum. Nor do any new structures appear 
in the stained preparation (iron-haematoxylin, as employed by Tschaschin). 
The color of the mitochondria is simply intensified by the iron-haema- 
toxylin. Since I am able to trace these same bodies into the composition 
of the spiral filament they are undoubtedly mitochondria. Moreover, 
numerous workers — among others, Faure-Fremiet (1910), Russo (1910), 
Ciaccio (1910) and Heidenhain (1911) — have remarked on the “lipoid 
nature” of these bodies. Tschaschin’s method of differentiating between 
yolk-granules and chondriosomes seems of very doubtful value and limited 
application. More will be said respecting the staining quality of the 
granules below. 
On the basis of his observations on Euchistus where the mitochondria 
are said to be formed about the idiozome in the early growth period 
of the primary spermatocyte, Montgomery proposes as a working 
hypothesis that those cells become germ-cells which get little or no 
mitochondria. 
