ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
495 
BOTANY. 
A. GENERAL, including- the Anatomy and Physiology 
of the Phanerogamia. 
a. Anatomy. 
(1) Cell-structure and Protoplasm. 
Streaming of Protoplasm and Transport of Nutritive Substances.* 
Commenting on the observations of Hauptfleisch on this subject,'!' Herr 
F. Kienitz-Gerloff brings forward additional arguments in favour of his 
previous view — as opposed to that of Pfeffer — that the streaming of 
protoplasm is a general phenomenon in all living cells, and that the 
protoplasmic connections from cell to cell assist in the transport of food- 
materials. External irritation may produce a double effect on the 
streaming of protoplasm, first retarding and then accelerating it. 
Reduction of the Chromosomes in Nuclei. J — Mr. E. Overton refers 
to the researches of Guignard, Strasburger, and others, which show that 
a reduction in the number of chromosomes or chromatin-segments takes 
place in connection with the development of the reproductive cells of 
Angiosperms. He has followed out a similar line of investigation in 
Gymnosperms ( Ceratozamia , Tsuga, Larix , Ephedra ), and finds that a 
similar reduction takes place in the mother-cells of the pollen, and 
persists through the whole male gametophyte. In the endosperm this 
reduction occurs in the earliest stages of its development, whereas the 
nuclei of the cells of the nucellus and of the integument have the full 
number of chromosomes. The reduction is, therefore, probably effected 
duriug the formation of the embryo-sac, and persists throughout the 
whole female gametophyte or endosperm, includicg the oosphere. As 
far, therefore, as investigation has at present been carried, the sexual 
and the non-sexual generations in Gymnosperms differ in the nuclei of 
the latter containing twice as many chromosomes as do those of the 
former. In Pteridophyta and Muscinese it seems probable — although 
the investigation is attended with considerable difficulties — that the 
reduction takes, place in the spore-mother-cells, and also persists 
throughout the gametophyte. 
Pectic Substances in Tissues. § — Pursuing his researches on the 
properties and distribution of pectic substances in plants, M. L. Mangin 
has, by the process already described, || demonstrated their presence in 
plants belonging to all the chief divisions of the vegetable kingdom,— 
Phanerogams, Vascular Cryptogams, Muscinete, and Thallophytes, and 
in all the tissues the membrane of which is not hardened by lignin or 
suberin. The chief exceptions to the presence of these substances are 
furnished by some classes of Fungi — Peronosporete, Saprolegnieas, Peri- 
sporiaceae, Uredinese, and Ustilaginete — and by certain hairs, as those of 
cotton. The membrane of soft tissues — parenchyme, collenchyme, bast, 
* Bot. Ztg., li. (1893) l te Abtheil., pp. 36-42. f Cf. this Journal, ante , p. 344. 
t Ann. Bot., vii. (1893) pp. 139-43. 
§ Journ. de Bot. (Morot), vi. (1892) pp. 363-8; vii. (1893) pp. 37-47, 121-31 
(2 pis.). Cf. this Journal, 1892, p. 809. || Cf. this Journal, ante, p. 417. 
