ZOOLOGtY AND BOTANY, MICROSCOPY, ETC. 
499 
/3. Histology- 
Morphology of the Ceil.* * * § — The reviewer of this work in * Nature ’ 
is of opinion that M. F. Henneguy has produced a more complete work 
on protoplasm and the nucleus than any of his predecessors. The 
work represents, we are told, a course of thirty-one lectures given at 
the College de France in the winter of 1893-4, and is an admirable 
account of the state of our knowledge to that date. The author deals 
both with animal and vegetable protoplasm, with its chemical and 
physical constitution, with its structure, as well as with the nucleus, the 
change which it undergoes, and its relation to the cytoplasm, and with its 
division and its conjugation. There is a chapter on the most important 
hypotheses on the constitution of protoplasm. While giving a special 
section to the consideration of the effects of different kinds of reagents, 
he calls the attention of his readers to the importance of the study of 
living protoplasm, and of checking all their results by it. The reviewer, 
in dealing with some remarks of the author as to Weissman’s suggestion, 
that the Protozoa are immortal, remarks that, with the words death and 
individual a philosopher can do much, but it behoves practical men to 
keep a sharp look-out on the use made of these convenient terms. 
Studies on Cell-Bivision.f — Dr. B. Bawitz devotes the first of these 
studies to an investigation of the behaviour of the attraction-sphere in the 
division of the salamander’s spermatocytes. He is strong in his conviction 
that the attraction-sphere is a morphologically definite structure, and that 
it has a definite function. In the beginning of chromosome-formation, 
the sphere attracts the first chromosome-rudiments. An important 
detailed result is the evidence showing that the polar corpuscles cannot 
with any certainty be derived from the centrosomes. An extra-nuclear 
spindle is formed (as to its fibrillar portion) from the cell-substance sur- 
rounding the sphere, and at the apices of the spindle portions of the sphere 
appear as polar-corpuscles. That these arise from the sphere is certain ; 
the possibility of their derivation from the centrosome is a moot jroint. 
Reducing Divisions.:]: — Prof. J. Riickert replies to recent criticisms 
by Hacker and vom Path. He maintains that in the case of Copepods 
the matter is fairly clear. There is essentially but one mode of matu- 
ration — that namely in which the tetrad groups appear in the form 
of transversely dividing double rods, ; in some forms there 
is this modification, that the single rods are united for a time by their 
free ends, forming a ring, <>. Into Riickert’s discussion with his 
critics we cannot, however, enter. 
Yolk-Nucleus and Polar Rings.§ — Miss Catherine Foot has pre- 
pared the present paper in the hope of proving that the polar rings and 
the so-called yolk-nucleus are one and the same substance. These 
results differ radically from those obtained by Mr. Calkin, from his study 
of the ovarian egg of Lumbricus, since he regards the yolk-nucleus as 
chromatin in the form of granules. In Allolobophora feetida, Miss Foot 
* ‘ Le 9 ons sur la Cellule, Morphologie et Reproduction,’ &c. Paris, 1896, 
xix. and 541 pp., 362 figs. See Nature, liv. (1896) pp. 193 and 4. 
f Arch. f. Mikr. Anat., xlvii. (1896) pp. 159-80 (1 pi.). 
X Tom cit., pp. 386-407. 
§ Journ. of Morpliol., xii. (1896) pp. 1-16 (1 pi.). 
