3x2 BOTANICAL GAZETTE [APRIL 
may be two kinds of perception, of which that by heavy starch grains alone leads 
to curvature, the other (e. g., by radial pressure) leads to the chemical changes 
—a strained answer. After defending his ideas against some criticisms by NOLL 
and by Mrrue, he pays his compliments to WresNER’s objections based on Clivia 
nobilis and C. miniata, the former being geotropic, while the latter is not. But 
NeéEmec finds both confirm the statolith theory, inasmuch as in C. nobilis there 
is abundant motile starch in the perigonial leaves, and none in C. miniata. Stato- 
lith starch is found widely distributed in mosses. It is wanting in certain geotropic 
liverworts (Metzgeria furcata), abundant in the strongly it ie T richocolea 
tomentella, and scarce in the weakly geotropic Plagiochila —C. R. B. 
STRASBURGER”? gives a popular but strictly scientific Aaa of the genus 
Alchemilla as it occurs on the Grand Saléve at Geneva. At least thirty-one 
species of this genus are found on this one mountain where Lrnn£é recognized 
only three. No wide gaps separate these species, but their distinctive characters 
are fully constant in inheritance. The author contrasts the Linnean conception 
of species as an abstraction with the present conception in which a species is & 
real entity which he defines as a group of individuals that agree among them- 
selves, and are separated from other species by definite characters that they 
inherit, however slight these characters may be. The species of Alchemilla are 
believed to be the result of a rather recent period of mutation, the evidence of its 
recency being found: (t) in the want of marked gaps between the species, which 
would result through the extinction of some species by natural selection; (6) 
the almost perfect development of stamens rendered functionless by the apog- 
amous habit of nearly all species; (c) the marked development of nectaries that 
are likewise functionless and secrete no nectar. The species are regarded as 
apogamous rather than parthenogenetic since no reduction of the chromosomes 
curs. No case of parthenogenesis in this sense is yet known among higher 
plants. Alchemilla is paralleled with two other noteworthy apogamous genera, 
Taraxacum and Hieracium, both of which likewise show numerous elementary 
forms, and it is suggested that the apogamous habit of these genera may have 
resulted through excessive mutation that introduced continuous hybridizations 
with attendant deterioration of the sexual processes.—G. H. SHUL 
IN AN ADDRESS before section K of the British Association, WARD’ has given 
an extremely interesting review of the growth of our knowledge of parasitism 
among the fungi and bacteria, from the researches of DEBARY to the sel 
time. The first part of the paper deals with the more important earlier dis- 
coveries which have marked distinct phases or epochs in the advancement of this 
subject, notably those of A. BRauN, DEBARY, TULASNE, ConN, Kocx, and ene 
a1 SrrasBuncer. E., Unserer lichen Frauen Mantel. Eine phylogenetisch¢ 
Studie. Naturw. Wochenschr. 20 : 49-56. 1905. 
23 Warp, H. MARSHALL, Recent researches on the parasitism of fungi. An?- 
of Botany 19:1~54. 1905. 
