. 954 REVIEWS. 
As to the special part, it would have been useful if a fuller account had 
been given of the structure and character of plants in relation to the fossil 
forms without the student having to refer to the * Class Book of Botany ;’ 
and also ifa synopsis with short descriptions of the families and genera 
had been giv 
u 
that the observer should be conversant with the conformation and deve- 
lopment of the living ones now on the earth ; with their habits, modes of 
existence and reproduction, the microscopic structure of their tissues, their 
distribution, and their relation to soil, the temperature, atmosphere and 
climate." J. M. 
Die Entwicklung des Keimes der Gattung Selaginella, (The Development 
of the Embryo of the genus Selaginella.) By W. Prerrer. Bonn: 
Adolph Marcus. 1871. (Hanstein’s ‘ Botanische Abhandlungen.’) 
here is perhaps no subject of more interest and importance to the 
botanist, yet fraught with more difficulties than the sexual reproduction 
of the Cryptogamia. Year by year difficulties are being overcome and 
more light thrown on those obscure yet wonderful reproductive processes 
which characterize the flowerless plants. We know absolutely nothing of 
the sexual reproduction of Lichens, and but little about these processes n 
many Fungi and Alge. As characters derived from the vegetative organs 
are only of secondary importance, it follows that we are only very gradually 
approaching a morphological classification of the Cryptogams. Take the 
classification of Cohn, given at pp. 114, 115 of the Journal of 
tany, and you will see in it an attempt to place due importance 0n 
characters taken from the reproductive organs. Why should a group 
called Alge exist when within that one division most varied and diverse 
modes of reproduction exist? Conjugation in one serie hogyne, 
cystocarp, and non-motile spermatozoids in another ; active spermatozoids 
and an oögonium in a third. Take 4 , by some considered a Fungus, 
the like, and then compare the conjugation in the moulds. Taken 
this way, Cohn's classification, even although it startles one at first sight, 
‘shows evidence of careful thought and much study. 
Pfeffer’s paper is one which contributes to our knowledge of the re- 
difference in the spores, as he h 
rminate. Hoffmeister worked well at the subject, describing the pro" 
thallium with archegonia, ete.; Millardet,one of the most recent observ x 
fully describing the germination of the microspores and formation of 
spermatozoids. 
