SCIENTIFIC SUMMARY. 
387 
adapted to such a laborious undertaking. He bases his classification upon 
certain characters of the male and female floral organs ; thus we find the 
groups Monandrce , Diandrae , and Polyandroe. The Diandrse are further 
divided into sub-groups characterized by peculiarities of the female por- 
tions of the flower. Dr. Andersson’s memoir has, we believe, been pre- 
sented to the Royal Academy of Stockholm. 
“ Struggle for Life” among Plants . — That Mr. Darwin’s views in regard 
to the mode in which one type of animals replaces another are now gene- 
rally accepted, is, we believe, well known to all our readers. That his 
opinions on this subject are equally applicable to plants has been shown 
by Dr. Hooker, in a late memoir. In treating of the mode in which this 
substitution occurs, the author alludes more particularly to the spread of 
European plants in New Zealand, and gives the following most interesting 
quotation from the writings of a correspondent : — <{ You would be sur- 
prised at the rapid spread of European and other plants in this country. 
All along the sides of the main lines of road through the plains, a poly- 
gonum called Cow-grass, grows most luxuriantly, the roots sometimes two 
feet in depth, and the plants spreading over an area from four to five feet 
in diameter. The Dock is to be found in every river-bed * * * * * 
The Sow thistle is spread all over the country, growing luxuriantly nearly 
up to 6,000 feet. The water-cress increases in our still rivers to such an 
extent as to threaten to choke them altogether. * * * * I have 
measured stems twelve feet long and three-quarters of an inch in diameter. 
In some of the mountain districts where the soil is loose, the white clover 
is completely displacing the native grasses, forming a close sward. * * * 
In fact, the young native vegetation seems to shrink from competition with 
these more vigorous intruders.” It appears to be a saying among the 
native population of New Zealand that, as the white man’s rat has driven 
away the native rat, so the European fly drives away our own , and the clover 
kills our fern , so will the Maoris disappear before the white man himself . — 
Natural History Review , No. xiii. p. 123. 
Peculiar Form of Asplenium Ruta-mur aria. — In May last, Mr. F. J. Foot 
communicated to the Natural History Society of Dublin a short paper, 
descriptive of a new variety of this handsome fern. The specimen laid 
before the society was unquestionably the A. ruta-muraria , but consi- 
derably modified, the upper pinnules resembling both in form and texture 
those of A. germanicum. The variation is more remarkable, from the 
circumstance that there appeared to be no external influence adequate to 
explain the alteration of specific characters. 
What is Palmogloea macrococca ? — An attempt to solve this very difficult 
query has been made by that indefatigable microscopist, Mr. Wm. Archer. 
The paper in which the solution of the difficulty is essayed is accompanied 
by a beautifully-executed plate, delineating the characters and develop- 
ment of Mesotosnium chlamydosporum , which Mr. Archer believes the 
above-named plant to be identical with. The original memoir, which is 
of considerable length, and may be almost regarded as a resume of what is 
known upon the subject, should be consulted by those interested in micro- 
scopic botany. — Vide Dublin Quarterly Journal of Science, Jan. 1864. 
Growth of Peruvian Cotton in India. — • Mr. Clements Markham has 
