434 EDWARD E. WILDMAN 
that this may occur, but he thinks it is not probable because 
the yolk forms first at the periphery of the cell. 
Marcus thus approaches very closely the true origin and nature 
of the refractive body. He lacked only the actual observation 
of the escape of the ‘trophochromatin’ or karyochondria from 
the nucleus into the cytoplasm, and the formation from this of 
the refractive vesicles, to complete his history of the refractive 
body in Ascaris canis. As we have seen, this gap is filled by 
this study of A. megalocephala. .If it be true that the yolk ves- 
icles first appear near the cell wall in A. canis, it must be due to 
chance aggregation of them there as a result of protoplasmic move- 
ment. The smaller granules from which others would be derived 
must be scattered throughout the cell, though these might have 
been overlooked. 
At any rate, the suggestion of Marcus is the correct one— 
borne out fully, I believe, by the observations recorded in this 
paper—that the refractive body plays no essential part in ferti- 
lization, but that it is merely a food supply for the spermatozoon 
alone, derived from the cytoplasm through the activity of a sub- 
stance which escapes from the nucleus, the karyochondria. 
THE ‘MITOCHONDRIA’ 
When spermatocytes are stained in iron hematoxylon alone, 
after fixation in an acetic mixture, and destained almost com- 
pletely, one finds small dense granules in the refringent vesicles 
which stain black. In those cells which are approaching divi- 
sion the vesicles are slightly oval, and the granules arrange them- 
selves in chains or rods which lie in the long axes of the vesicles. 
They are most conspicuous during the metaphase of the second 
maturation division, because at this time the refringent vesicles 
are arranged concentrically around the centrosomes, and the 
chains of granules are therefore perfectly radial with respect to 
these (fig. 34). 
But during the anaphase of this division the chains of granules 
are drawn out of the vesicles and break up, and the separate 
granules crowd close up to the chromatic mass, but in radial and 
concentric lines. The refringent vesicles, also acted upon by the 
