1899] CURRENT LITERATURE 439 
and Paronychiee growing in deserts resemble each other and also those on 
alpine heights, for in high altitudes the sun’s rays are very powerful and 
plants need the same protection as in deserts. On the other hand, specimens 
of the same species, under various conditions, show extreme divergence. 
He also shows that many species of the Primulacew resemble those of the 
Caryophyllaceze when grown under like conditions. Only a causal depend- 
ence between situation and structure can explain such resemblance, since 
common origin cannot do it.— L. M. SNow 
SEEDS whose viability had been previously tested by samples were recently 
submitted by Professor Dewar to the intense cold of liquid hydrogen, z. ¢., 
— 250°C. for half an hour. Some of the seeds were cooled in a sealed glass 
tube, and others were immersed without protection in the liquid hydrogen. 
All the seeds in both sets germinated. —C. R. B. 
THE LITERATURE of diatoms has recently been enriched by a very 
important contribution.?. The work is not merely a guide for the determina- 
tion of the species of a limited locality, but is a comprehensive text-book of 
diatom lore. The author has departed from the usual comparatively super- 
ficial methods, and has taken into account the form and structure of the pro- 
toplast, the position of the nucleus, the number, form, and position of the 
chromatophores, the occurrence of pyrenoids, and, finally—a most important 
consideration—the complete life history of each species as far as this has 
been possible. A study of cell characters convinced the author that the 
number and position of chromatophores is the most important taxonomic 
character, and that mere frustule characters are not sufficient for determining 
the limits of species. 
The second part of the work gives a somewhat extended account of the 
diatom cell, cell division, movements of diatoms, the relation of variety of 
form to environmental factors, the auxospores, and the role of diatoms in the 
economy of nature. CHARLES J. CHAMBERLAIN, 
THE PRODUCTION of apospory by environment has been brought about 
in various ferns. Mr. F.W. Stansfield® has succeeded in producing apospory 
in Athyrium filix-femina, unco-glomeratum, an apparently barren form. In 
all cases it was noted that prothalli are produced with much more ease from 
young fronds than from adult ones. If the first fronds from a prothallus are 
Pinned down, the edges rapidly develop into prothalli. The aposporous eu 
duction of prothalli is regarded as: an atavistic trait, and the nae eter . 
made that apospory could be produced in many ferns by demise em 
Bucht. Wissenschaftliche 
STEN, GEORGE; Die Diatomeen von Kieler S 
7KarR 
Meeresuntersuchungen herausgegeben von der Commission zur Untersuchung 
deutschen Meere in Kiel und der biologischen Anstalt auf Helgoland, Abtheilung 
Kiel. Neue Folge 4: 19-295. figs. 219. 1899. 
*Jour. Linn. Soc, Bot. 34: 262-268. 1899. 
