750 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
micellae of a starch-grain is apparently the large size of its micellae ; 
it can, however, under sufficient pressure, permeate the cell-wall. The 
ferment belongs to the class of colloids. As regards its transmission 
from one part of the plant to another, this cannot take place in the 
form in which it converts starch into sugar ; in order to be transported 
it must undergo some chemical change, and be again restored to 
the fermentative form at the spot where it resumes its activity. But it 
is not certain that it ever is transported from one part of the plant to 
another. 
Gum-ferment.* — From an examination of the processes which take 
place in the living plant, with the assistance of staining reagents, Herr 
F. Reinitzer contests the view that the formation of gum and mucilage 
is due to the action of a definite ferment. 
y. General. 
Alternation of Generations-! — Prof. F. 0 . Bower points out that 
under this term many writers include phenomena of two different 
kinds, which he proposes to call antithetic and homologous alternation of 
generations. In antithetic alternation we have two phylogenetically 
distinct generations, i. e. a new stage (the sporophyte) has been inter- 
polated between pre-existing generations (the gametophytes or oophytes) ; 
this has probably arisen independently in several distinct phyla, and 
the results are not perfectly comparable with one another. It occurs in 
the Arcliegoniatae, the green Confervoideae, &c., the Florideae, and the 
Ascomycetous Fungi. In homologous alternation we have two or more 
phylogenetically similar generations, but differing in the presence or 
absence of sexual organs. It is found in the Thallophytes, e. g. Botry- 
dium, and might be described as a mere differentiation, often a very 
slight one, of successive gametophytes. The axis and leaf of the 
gametophyte in the Muscinem are not the true homologues by descent of 
the axis and leaf of the sporophyte in Vascular Cryptogams, although 
performing the same physiological function ; and the author proposes 
restricting the terms caulome and phyllome to the latter, and terming 
the former “ caulidium ” and “ phyllidium.” 
The late Mr. J. R. VaizeyJ expressed views on the whole similar to 
those of Prof. Bower. He regarded Chara as being, in all probability, 
connected with the FlorideaB ; and the morphological position of its 
embryo as that of an embryonic stage in the development of the 
oophyte, corresponding to a certain extent with the protoneme of true 
Mosses. 
B. CRYPTOGAMIA. 
Cryptogamia Vascularia. 
Apical Growth in Marsilea and Equisetum.§ — Mr. W. M. Andrews 
finds the phenomena of the apical growth in roots of Marsilea qua- 
drifolia and Equisetum arvense somewhat different from those described 
by de Bary and Goebel. 
* Zeitschr. f. Physiol. Chemie, xiv. pp. 453-70. See Bot. Centralbl., xliii. (1890) 
p, 117. t Ann. of Bot., iv. (1890) pp. 347-70. 
x T. c., pp. 371-8. § Bot. Gazette, xv. (1890) pp. 174-7 (2 figs.). 
