64 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
BOTANY. 
A. GENERAL, including* the Anatomy and Physiology 
of the Phanerogamia. 
a. Anatomy. 
CD Cell-structure and Protoplasm. 
Reduction of the number of Chromosomes in Plants.* — Prof. E. 
Strasburger gives a detailed review of recent observations on the periodic 
reduction of the number of the chromosomes in the life-history of living 
organisms. He considers the fact as established that the number of 
chromosomes characteristic of the generative nuclei of Angiosperms is 
determined, in the one case, in the mother-cells of the pollen -grains, in 
the other case, in the mother-cells of the embryo-sacs, corresponding to 
a similar phenomenon in the animal kingdom. The physiological utility 
of this reduction is evidently that it prevents the number of chromosomes 
in the nuclei of each generation becoming twice as great in the pre- 
ceding generation. Morphologically it indicates a return to the original 
generation from which, after it had attained sexual differentiation, 
offspring was developed having a double number of chromosomes. The 
reduction by one-half in the number of chromosomes takes place, in the 
Muscineae, Pteridophyta, and Phanerogamia, in the spore-mother-cells, 
i. e. at the close of the generation developed from the fertilized ovum ; 
but in the lower Cryptogams, where the cell produced by the sexual act 
does not give rise to a definite organism representing the non-sexual 
generation, the reduction probably takes place on the germination of 
this cell. 
Seeing that it is in the mother-cells of the spores that the reduction 
takes place in the higher plants, it is these which must be regarded as 
the first term of the new generation; their true significance in this 
respect being indicated by the fact that they usually isolate themselves 
from cohesion with other cells. This greatly reduces the significance 
of the archespore or mass of cells which gives rise to the sporogenous 
tissue, and which still belongs to the sexually developed non-sexual 
generation. It is simply the merismatic tissue from which the spore- 
mother-cells are derived. 
Centrospheres in Fungi.f — Mr. H. Wager describes certain peculiar 
bodies accompanying the process of nuclear division in the basids of 
Agaricus reticulatus , which appear to indicate the presence of centro- 
spheres or kinetic centres in the vegetative cells of Fungi. They are 
apparently of archoplasmic nature, and are found singly or in pairs 
just outside the nucleus, and generally in close contact with it before 
division has commenced. They appear to consist of a homogeneous 
mass of substance, spherical in outline. There is no indication in them 
of any medullary corpuscle or centrosome ; but they present a strong, 
resemblance to the archoplasmic bodies described by various writers in 
* Ann. Bot., viii. (1894) pp. 281-316. Cf. this Journal, 1894, p. 5S3. 
f Torn, cit., pp. 321-34 (1 pi.). Cf. this Journal, 1894, p. 380. 
