100 MCMURRICH. [VoL. XIV. 
A. B. Lee (95) has taken exception to the interpretation 
given by Ryder and Miss Pennington, but has erred quite as 
greatly as the original authors in the explanation which he . 
gives. He supposes the bands of nuclear substance, which 
they have figured as extending from one cell across the 
boundary into another, to be persistent nuclear spindles. 
The examination of a single preparation of the ‘midgut’ 
of a land Isopod which showed the phenomenon, and they | 
are not difficult to obtain, would have shown Lee at once that 
his conclusion was an untenable one, and he might have saved 
himself from a too hasty generalization. The bands are undoubt- 
edly nuclei, and resting nuclei at that, staining intensely with 
the usual nuclear stains, and not requiring the use of the 
Kernschwarz for their unmistakable demonstration. 
The true significance of this supposed nuclear conjugation, 
which after all is based merely on the occurrence of nuclei 
which pass across the apparent boundary between two cells, 
may be understood when we recall two peculiarities of the 
“midgut” epithelium, namely, that it is a syncytium, and that 
its nuclei are capable of extensive amoeboid movement. These 
movements are undoubtedly at times quite vigorous, if we may 
judge from the remarkable shapes which the nuclei present; 
and there being no true cell boundaries, there is no mechanical 
obstacle in the way of one nucleus invading the territory of 
another. This, I believe, is simply what happens, and there 
does not seem to me to be the slightest ground for assuming 
that any such remarkable process as a nuclear fusion takes 
place in the adult and remarkably modified cells of the ‘“ mid- 
gut” of the terrestrial Isopods. 
A few words yet remain to be said concerning the minute 
structure of the nucleus. A well-defined membrane surrounds 
every nucleus (Figs. 2, 10, zw), and the nuclear contents seem 
to be composed of four substances. In the first place there is 
a considerable amount of caryolymph, not infrequently aggre- 
gated to form intranucleolar vacuoles, a peculiarity especially 
noticeable in one preparation I possess from /dotea robusta, two 
cells from which are represented in Fig. 6. In nearly every 
nucleus the caryolymph seems more abundant towards the 
