102 
POPULAR SCIENCE REVIEW. 
it will be concluded, but it will not be issued oftener than once in every 
six months. It is a work which every lover of fungi should possess. 
The Atlas of Diatomacece . — Several parts of this excellent work have 
now been published, and Mr. Kitton, one of our best authorities on the 
subject, gives this work very high praise indeed in a notice published in 
tl Grevillia.” Certainly the plates, though a trifle rough, appear excel- 
lently executed, and they contain enormous magnifications of the objects 
illustrated. The number of illustrations is numerous in each part. 
Influence of Nutrition on Form . — At a recent meeting of the Academy of 
Natural Sciences of Philadelphia, Mr. T. Meehan remarked that the influence 
which nutrition, in its various phases, had on the forms and characters of 
plants was an interesting study ; and in this connection he had placed on 
record in the Proceedings of the Academy, that two species of Euphorbia , 
usually prostrate, assumed an erect growth when their nutrition was inter- 
fered with by an JEcidium — a small fungoid parasite. He had now to offer 
a similar fact in connection with the common Purslane ( Portulaca oleracea ), 
one of the most prostrate of all procumbent plants, which, under similar 
circumstances, also became erect. 
Some neiu Plants from the Nicobar and Andaman Islands .- Herr S. Kurtz 
has a very interesting paper on this subject in the “ Journal of Botany ” for 
November 1875, from which, however, we only abstract some of the phy- 
sical facts recorded. The most remarkable one is the nature of the clay. 
Herr Kurtz says that the interest which attaches to the Nicobar vegetation 
rests chiefly in the peculiar polycistine clay, which looks somewhat like 
meerschaum, and is also nearly as light and porous. This clay covers large 
areas on those islands which form the so-called northern group. It contains, 
according to Dr. Bink’s analysis — 
Silica 722 
Oxide of iron 8-3 
Alumina 12-3 
Magnesia 2T 
Water 56 
100*5 
Here the total absence of alkalies is very remarkable. In places it be- 
comes red from abundance of oxide of iron, and in this case it is usually 
literally filled with fossil seaweeds. A microscopical examination of the 
rock reveals abundance of silica, fragments of polycistines, and diatoms. 
One would say that on such substrata nothing but wretched scrub and harsh 
grasses could vegetate ; but an examination of the greater part of Kamorta 
has taught me that luxuriant tropical forests, with an average height of 
about 80 ft., not only cover the seaside, but the same forests form belts of 
considerable breadth over the island itself, while the inner hill plateau is 
covered by those peculiar park-like grasslands which Dr. Diedrichsen has 
called grass-heaths. The next rocks botanicallv influential are calcareous 
sea sand, raised coral banks, limestone and calcareous sandstones, which be- 
long to the so-called southern group, in which, however, Katchall (an entirely 
calcareous island) is enumerated. Then come the plutonic rocks and their 
