40 The Botanical Gazette. (February, 
Evolution in methods of pollination. 
ALICE CARTER. 
In attempting to arrange our phanerogams in a natural 
order, I have been astonished at the close resemblance even 
in external appearance between the reproductive organs of 
moss-like or frond-like form of degenerate water plants, e. g., 
Lemna, Wolffia and Myriophyllum. The essential similarity 
in the life processes of all the higher plants, pteridophytes | 
and phanerogams, is a fact familiar since the dayS of Hof-+ 
meister, and is constantly receiving confirmation. For 
instance, Stengel has recently described the beautiful transi- 
tion in anatomical structure and origin between the macrospo- 
rangia (ovules) of gymnosperms and angiosperms. The 
discovery of such analogies is one of the great achievements 
of modern botany, making it possible, by embryology and 
histology, to trace the ascent from mosses to exogens, pictur- 
ing to us the development which geology shows has been 
going on in time. 
Variation is the source and presupposition of this develop- 
ment. Change of conditions and cross-fertilization are the 
two great known causes of variation. The first, in the case 
of fixed plants works slowly; the second includes within itself 
the advantages of the first and others of its own; for by it the 
characteristics of dissimilar parents, whose differences are to 
a certain extent the results of the dissimilarity of the condi- 
tions to which they have been subject, are transmitted in va- 
rying proportions to succeeding generations. New properties 
are thus acquired and old ones changed, and the variable 4 
descendants of crossed -plants conquer the unimproved 
offspring of self-fertilization, 
The process of conjugation in the lowest plants in which there 
is a sexual reproduction, in almost all cases makes probable the 
union of the spores of two distinct individuals (Spirogyra, Mu- 
cor, Desmidiacee, Diatomacee, etc. ), while the same possibility 
