202 ADAM SEDGWIOCK. 
rangement. This at any rate is my view for the Peripatus 
nucleus. 
Klein figures (10, Pl. 18) nuclei from the epidermis of the 
newt in a state of direct division. These figures resemble very 
closely some of the endodermal nuclei in the gastrula of Peri- 
patus. 
Klein is still more explicit as to the continuity of the nuclear 
and extra-nuclear reticulum in his second communication on 
this subject (11, p. 416). 
Unfortunately I have not been able to see the papers of 
Stricker and Heitzmann. 
Leydig in his latest communication (12) regards the spindle- 
fibres as parts of the ordinary reticulum (spongioplasma he 
calls it) with much elongated meshes (p.9). He further looks 
upon the nuclear membrane as merely the outer portions of 
the nuclear network, and describes it as being porous, and 
takes the same view as Klein with regard to the continuity of 
the nuclear and intra-nuclear network. 
Leydig also describes some accessory nuclei as occurring 
in certain cells. These are smaller than the main nucleus and 
stain less deeply. It is possible that they are structures of 
the same nature as those described in the endoderm of Peri- 
patus on p. 184 of this memoir. 
He refers, in this connection, especially to the small acces- 
sory nuclei which are found in many Protozoa, and which, 
according to Gruber (3) and Jickeli (7), are for the most part 
derived from the breaking up of the main nucleus. The parti- 
cles resulting from this fragmentation of the nucleus seem 
eventually to come together again to form a new main nucleus. 
One would like to have some more details about this peculiar 
process in Infusoria, derived if possible from the study of 
sections. The term “ fragmentation,’ which is applied to it 
apparently because the chromatic parts of the nucleus become 
separated from one another and scattered throughout the 
animal, seems to imply a distinct breaking up into small 
isolated portions. If this really happens the nucleus of Infu- 
soria must differ from most other nuclei in which the chromatic 
