ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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refractive than the nuclear sap ; in the framework there are found 
chromatin granules ; there is a delicate nuclear membrane. 
(3) Nuclei with the chromatin condensed in an irregular clump, in 
the centre or at the side of the membrane ; from this clump linin threads 
radiate through the nuclear cavity, and are attached to the membrane. 
(4) Nuclei with the chromatin in homogeneous compact spherules 
(1-5 ix in size, 20-100 or more in number) ; these lie on the membrane, 
while the central part is filled with colourless, structureless nuclear 
sap. 
Division of Ceratium.* — Herr R. Lauterborn has investigated the 
division of cell and nucleus in Ceratium Jiirundinella. The resting nucleus 
has a fine-meshed, reticular-webbed structure, with one or two nucleoli 
which may be central or peripheral in position. Division occurs at 
night. The nucleus increases in volume ; its regular structure becomes 
a tangled coil; the nuclear threads arrange themselves approximately 
parallel to the shorter axis, so that the nucleus appears fibrous. Fine 
connections are seen between the nuclear threads, nucleoli are still visible 
at the poles, and there is an obscure rod-like body, visible in picrocar- 
mine preparations, which often appears divided in later stages. The 
shorter axis of the nucleus, the subsequent division-axis, lies at an angle 
of about 4.5° to the transverse groove of Ceratium , from left above to right 
below. It elongates in the direction of the division-axis ; the nuclear 
threads are constricted at the equator ; the daughter-nuclei go apart. An 
oblique constriction from left below to right above divides the plasm. In 
one case where the constriction had reached the middle, a distinct inter- 
mediate body was seen. The shell is split along a definite oblique line, 
approximately parallel to the division-plane of the plasm. Marginal 
regeneration begins at once, furrow and horns soon appear, and with 
further growth complete separation of the daughter- individuals is 
effected, each with a shell partly old, partly new. 
It will be noted that the division is not direct, as Blanc said, nor 
strictly mitotic, as Zacharias reported. Thus no longitudinal cleavage 
of the chromatin-elements was observed, nor an achromatic spindle. It 
suggests the division of the macronucleus in Ciliata. 
Coccidia met with in Mice.j — Mr. J. Jackson Clarke, on dissecting 
a white mouse kept in a place previously occupied by rabbits, found large 
numbers of Coccidia in every part of the alimentary tract beyond the 
cardiac opening of the stomach. Study of the parasites which were 
observed led him to conclude that they were probably identical with the 
Sporozoa described by Eimer in the intestines of mice and called Eimeria 
by Schneider. Eimeria itself is probably only a variety of Coccidium 
oviforme , and maybe but a modification of C. oviforme determined by the 
smaller dimensions of the epithelial cells of the intestine of the mouse, 
as compared with those of the rabbit. The appearance of large numbers 
of swarm-spores in the gastric glands of the mouse is very similar to 
that presented by the Sarcosporidia, and suggests that the latter is but 
one phase of a Sporozoon, which may have in other phases a form 
resembling that of the Coccidia. 
* Zeitschr. f. wiss. Zool., lix. (1895) pp. 167-90 (2 pis.). 
f Quart. Journ. Micr. Sci., xxxvii. (1895) pp. 277-83 (1 pi.). 
