532 THE AMERICAN NATURALIST. [Vow. XXXII. 
not so quickly nor to such an extent as under normal conditions 
of contact. 
The plants experimented with chiefly were: Uncaria sclerophylla, 
Ancistrocladus Vahlii, Roncheria Grifithiana, Artrabotrys Blumet, 
Strychnos monospermum, S. laurina, Amphilobium mutsit, Bauhinia 
tomentosa, Dalbergia linga, and Vanilla aromatica. EMR 
Apogamy in Ferns.!— A considerable series of cultures under 
varying conditions show that some, at least, of the conditions which 
induce apogamic development in fern prothalli are a deprivation of 
water sufficient to prevent the possibility of fertilization and the 
action of direct sunlight. Different degrees of apogamy are possible, 
from a cylindrical process still bearing sexual organs arising from 
the apex of the prothallus, to the condition where this process gives 
rise directly to the vegetative bud of the sporophyte. 
While the authors admit that, with certain assumptions, the theory 
of antithetic alternation, as advanced by Bower, affords a satisfactory 
explanation of the relation of the gametophyte to the sporophyte 
generation, they are inclined to favor more the idea of homologous 
alternation, namely, that the sporophyte arose gradually from modifi- 
cations of individuals resembling the sexual plant, and is not from a 
mere elaboration of the zygote. The line of evidence offered bears 
on the assuming of a terrestrial habitat by originally aquatic plants, 
whereby these plants, in adapting themselves to dryer surroundings, 
are forced to develop in the line of the production of dry repro- 
ductive cells (spores) rather than the more sensitive sexual organs. 
Hence the increase in size and importance of the spore-bearing 
plant, which eventually, by its own mass of vegetation, would afford 
shade, and consequently the conditions more suitable for the persist- 
ence of the primitive moisture-loving sexual stage. 
The authors conclude by saying that the question is still an open 
one and must remain so until more decisive evidence is brought for- 
ward by which either the theory of homologous alternation or that of 
antithetic alternation can be shown to be untenable. H. M. R. 
2 
A New Method for Preserving and Fixing Fresh-water Algæ. 
—This fixing agent consists of equal volumes of formalin, pyrolignic 
acid, and methyl alcohol. The algz are drained as far as is possible, 
without injury to them, from the water in which they grow, and 
1 Lang, W. H., and Clark, G. H. On Apogamy and the Development of 
pear upon Fern Prothalli, Bot. p a Bd. Ixxiv, Nr. 3, p. 72- 
Pfeiffer, Oesterreicher. Bot. Zeit., Bd. xlviii, Hefte 2 und 3, 1898. 
