58 
them as varieties and simply numbered them by Greek letters. 
Obviously the propositions in the Gardeners' Chronicle had not been 
thoroughly worked out. 
/ 
Sex in Plants. — Some interesting experiments have been carried 
out by F, Heyer {Journ, Microsc, Soe,, p. 251) with a view to deter- 
mine the cause of differentiation of sex in unisexual plauts. The 
result obtained in the case of dioecious plants, by experiments with 
21,000 specimens of Mercurialis annua and 6,000 of Cannabis Indica, 
was that external conditions have no influence upon the production 
of seedlings of one or the other sex. In the case of the former plant 
the proportion of males to females produced was as 105.85 to 100, 
and in the latter as 86 to 100. In a second series of experiments 
made with monoecious plants, to determine whether external con- 
ditions of temperature and soil caused any difference in the propor- 
tion of male and female flowers, Urtica urens, Atriplex, Spinacia, 
Xanjhium, and various Cucurbitaceae produced negative'results." He 
also^ came to the conclusion that sex is determined at an earlier 
period than the ripening of the seed. A knowledge of the means 
whereby female plants could be produced at will would be of con- 
siderable commercial importance, as, for instance, in the cultivation 
of nutmegs, hops, etc. 
A gigantic Plane-tree —Professor Virchow recently exhibited at 
a meeting of the Berlin Medical Society photographs of a gigantic 
plane-tree growing in the Island of Cos, under the shade of which 
Hippocrates is said, by tradition, to have held medical consultations. 
Thetree now stands in the market-place of Cos on the east side of 
the island. The branches, which spread over nearly the whole of 
the market-place, are supported by marble pillars. 
Botanical Literature. 
A Catalogue of the Native aud Naturalized Plants of the city of Buf- 
falo and its vicinity. By David F. Day. 8vo, pp. 215. Buffalo: 
Baker, Jones & Co. 1883. 
Of purely local floras, this, presenting the names of all the plants 
which have been detected within a radius of fifty miles of Buffalo, 
may be regarded as one of the completest that has ever been pub- 
lished in this country. All the classes in the vegetable kingdom are 
mcluded, and the number of plants enumerated, according to the 
tabular statement on page 190, is 2,739, which are distributed among 
946 genera. 
Mahonia Aquifolia as a Nurse of the Wheat Mildew ( Puccinia Gra- 
minis). By C. B. Plowright. (From Proceedings of Royal So- 
ciety, No. 228). 
On the Life History of the Dock ^cidium ( jEc. Rumicis), By C B. 
Plowright. (From Proceedings of Royal Society, No. 228). 
The Microscopical Bulletin and Opticians Circular. 
Under this title, the well-known opticians, Messrs. James W. 
Queen & Co., of Philadelphia, have recently begun the publication 
' of a bi-monthly which will prove of value and interest to all micro- 
scopists, and which will no doubt be well supported by them. 
Sample copies will be sent to those who request them. 
