70 The American. Naturalist. [January, 
the chromatin is massed on the opposite side and the nucleus is very 
large and vesicular containing many irregular dark-staining masses or 
nucleoli, which are frequently vacuolated. On the luminal side the 
nuclear membrane becomes so thin that it is impossible to say whether — 
it is continuous or not. Between the nucleus and lumen the cytoplasm 
is unusually dense and immediately outside of the nucleus it is massed 
into a dense darkly-staining substance, which projects by one or many 
processes into the cavity of the nucleus. These processes frequently 
contain vacuoles and in structure and staining qualities they exactly 
resemble the nucleoli. Frequently these processes are deeply con- 
stricted at the base as if they were about to be cut off and set free into 
the nuclear cavity, as indeed I believe to be the case. a 
The general similarity of this process to the reception of food material 
by the egg of Dytiscus as observed by Korschelt is at once apparent, — 
In this case, as in that, there is little doubt that the granular material 
is a nutritive substance, which, in the case of the Isopods, is taken up — 
from the alimentary canal and sent up in a broad band to the nucleus, 
where it aggregates immediately outside the nuclear wall. Unlike the — 
cases observed by Korschelt; however, this substance projects into the 
vesicular nucleus in the form of processes which appear to be cut off 
and set free within the nucleus. There are many reasons for believing — 
that this substance projects into the nucleus rather than that the nu- — 
cleus sends out pseudopodial processes into it. The nuclear wall is ab 
this place so extremely thin as to be absolutely invisible in many places, 
and the nucleus itself is of such an open and vesicular character that it 
seems scarcely possible that it should actively send out processes into 
this densely granular mass. Moreover the evidence that these processes _ 
are set free into the nuclear cavity seems to me very good, though, pe _ 
haps, not absolutely convincing. I shall leave the consideration of thé 
functional significance of this phenomenon to a future paper. 
DESCRIPTION OF FIGURES. 
Fig. 1. A small portion of the intestinal wall of Porcellio which had 
been gently pressed upon with a spatula. The entire intestine W 
similar to the bit here shown. Fixation, Corrosive-Acetic ; stain, Br 
ondi-Heidenhain ; Obj. 8mm.; Occ. 4 (all the figures were sketch 
with a camera lucida under Zeiss Apochromatic lenses). a 
Fig. 2. Longitudinal section through dorsal wall posterior to typhlo 
sole showing distorted nuclei. The contiguous cell boundaries atè 
marked only by the circular muscle fibres which are seen in cross-sec" 
tion. Fixation, picro-formalin; stain, Biondi-Heidenhain; Obj. Š 
mm.; Oce. 4. a 
