Notes . 
5 7i 
propagation by zoospores, conidia, &c., corresponds to the propaga- 
tion by buds in the Mosses and Ferns, and is not taken into account 
as regards the actual alternation of generations. 
Pringsheim takes up a quite opposite point of view (1876, 1878). 
According to his opinion the fruit of the Ascomycetes and Florideae 
has not the value of a special generation, but is only to be regarded 
as a part of the mother-plant sexually influenced. The true alterna- 
tion of generations of the Thallophytes consists, according to 
Pringsheim, in the regular succession of independent so-called neutral 
generations, having non-sexual propagation, and a single sexual 
generation. Thus, zoospore-forming generations of Vaucheria , or 
Oedogonium y alternate with a generation which bears the sexual 
organs. Both kinds of generations are of essentially similar structure ; 
they are distinguished by the form of their propagation. Only the 
first generation, which springs from the fertilized ovum, has often 
properties which differ from those which follow, e. g. in Coleochaete. 
In the Mosses this first non-sexual generation is much more sharply 
characterized; it is developed as the sporogonium, and is the only 
neutral generation ; it differs from the sexual generation only by the 
scanty development of the vegetative part, 
While the views of Sachs on the one hand, and of Pringsheim 
on the other, were showing some tendency to spread, other views 
appeared in opposition, now to one, and now to the other. Vines 
(1879) held that most of the Thallophytes have no alternation of 
generations at all, since their mode of propagation, whether sexual 
or non-sexual, is directly dependent upon external conditions; that 
a definite alternation of generations, comparable to that of the 
Mosses, is only found in Coleochaete and Char a. Celakovsky (1877), 
however, was more in accordance with Pringsheim in his conception 
of the Thallophytes, for like him he accepts an alternation of neutral 
and sexual generations. Celakovsky designates this alternation of 
generations as homologous, since the successive generations are 
equivalent to one another. Celakovsky opposes Pringsheim in his 
conception of the alternation of generations in the Archegoniatae, 
which he designates as the antithetic. Here the two alternating 
generations are not homologous, but essentially different; the non- 
sexual generation has also phylogenetically nothing to do with the 
neutral generations of the Thallophytes. This conception of Cela- 
kovsky was at first neglected, but was taken up again by Bower 
