788 THOS. H. MONTGOMERY, JR. 
stands under the influence of the chromatin plate. In Eu- 
schistus there is no evidence that the mitochondria are produced 
by emigrated chromatin particles, and indeed the idiozome 
intervenes between them and the chromatin plate. Also in 
this species they certainly have no relation to the idiochromo- 
somes, which may lie upon any point of the nuclear membrane 
except the idiozome pole and they do not discharge any visible 
substance into the cytoplasm.2t Were the mitochondria of 
strictly cytoplasmic origin it would be difficult to explain why 
they always arise at a particular pole of the nucleus near the 
chromatin plate and the idiozome. Therefore it seems a better 
working hypothesis to conclude that they are produced either 
by some chemical interaction of idiozome and cytoplasm, or 
of nucleus and cytoplasm, which would be, in either case, an 
ultimate nuclear origin. It is interesting to note that their 
period of early development in the spermatocytes corresponds 
with the period of conjugation of the chromosomes, and the 
latter process may be the initial step in their production. This 
is all in agreement with the concept of the nucleus as the par- 
ticular formative center of the cell. After the idiozome of 
Euschistus has disintegrated, and the chromatin plate become 
disestablished, the mitochondria becomes scattered throughout 
the cell, and then they become larger and more prominent, evi- 
dently by autonomous growth. Thus it may well be that the 
nucleus directly, or acting through the idiozome, gives off fer- 
ments in small amounts to the cytoplasm and these ferments in 
their turn engender the mitochondria that later become self- 
perpetuating structures. 
Another point of interest is how the mitochondria become 
distributed in the maturation mitoses. In neither Euschistus 
nor other forms is there evidence of autonomous division of them 
in mitosis; they appear rather to become divided passively by the 
equatorial constriction of the cell; there is no other mechanism 
for their division, for they lie outside of the spindle and are 
21 Both Buchner and Wassilieff hold the mitochondria to be produced by a pour- 
ing out of substance from the modified chromosomes, though Wassilieff’s results 
on Blatta have been contradicted by Morse. 
