ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
307 
which arc capable of being individually determined from the germ 
onwards. The determinants have a definite mutual arrangement in the 
germ-plasm, forming aggregates of a higher order, the “ ids.” It is 
probable that parts of the “ chromosomes ” are the “ ids,” and that the 
nuclear rods arc aggregates of “ ids,” which are spoken of as “ idants.” 
After a discussion of the germ-plasm, the author considers regeneration, 
multiplication by fission and gemmation, alternation of generations, the 
formation of germ-cells, amphimixis, reversion, dimorphism and poly- 
morphism, the transmission of acquired characters and variation. What- 
ever may be the opinion of biologists as to Weismann’s conclusions, it 
will be allowed by all that the book is rich in accumulated learning, 
ingenious argument, and bold speculation. 
In a short note * * * § Prof. Weismann discusses the share which Jager, 
Nussbaum, and others have had in developing the modern conception 
of heredity. 
Reproduction and Heredity. f — Dr. M. Nussbaum was one of those 
who several years ago (1880) directed attention to the organic continuity 
between generations — an idea which Weismann has done much to 
confirm and elaborate. What Nussbaum expounded, however, was a 
continuity of germ-cells, not of germ-plasm. To this he adheres, and 
in defending his own position criticizes Weismann’s recent book. He has 
also something to say as to the share which he, Jager, Weismann, and 
others have had in the historical development of our present conception 
of heredity. 
Histology. 
Cell-division4 — Prof. E. Strasburger reviews the present state of 
our knowledge of cell-division. Between animal and vegetable histology 
there is mutual influence, as has been illustrated lately in regard to 
attraction-spheres. For these the author proposes the more morpho- 
logical term “ astrosphere.” The cytoplasmic origin of the nuclear 
spindle — independent of the proper nuclear substance — is discussed. 
The division of the pollen-mother -cell in a lily is sketched. Strasburger 
is inclined to regard the movement of the nuclear segments as active, 
under the influence of a chemotactic stimulus from the centrospheres. 
The substance which forms the spindle-fibres, and which in plants is 
cytoplasmic, not nuclear, Strasburger calls kinoplasm. It seems to be 
the same as Boveri’s archoplasm. Various recent researches are sum- 
marized in this paper. 
Imitation of Karyokinetic Figures. — Prof. 0. Biitschli § has been 
able to mimic centrosomata and attraction spheres in gelatin-oil foams. 
The contraction of a central air-bubble produces surrounding radiations. 
Dr. H. Henking j| has got similar appearances by letting drops of 
alcoholic solution of shellac or some other fluid fall on a smoked surface 
of paper or glass. In this case the radiations are due to expansion, not 
to contraction. Some photographs of the imitations are appended, so 
* Ber. Nat. Gesell. Freiburg, vii. (1893) pp. 36-7. 
t Arch. f. Mikr. Anat., xli. (1893) pp. 119-45. 
X Anat. Anzeig., viii. (1893) pp. 177-91. 
§ Verh. Nat. Med. Ver. Heidelberg, v. (1892). 
|| Arch. f. Mikr Anat., xli. (1893) pp. 28-39 (1 pi.). 
Y 2 
