CHLOROSPERMEJE. 
3 
now been discovered in several, leading to the inference that they exist in all. In some 
cases the spermatozoids are directly formed within the cells of the frond, from which they 
are dispersed in the water, and find their way to the enlarged cell in which the nucleus 
of the future spore, or rather sporangium , is contained, and which they penetrate, and 
effect the fertilization of the contents. In other cases there are formed within the cells 
of the frond and emitted into the water, solitary male-producing bodies resembling 
zoospores in form, but of smaller size, to which Pringsheim gives the name androspores. 
These androspores , after swimming freely for some time, like the zoospores, affix them- 
selves (in (Edogonium ) to the surface of the enlarged cell containing the female nucleus, 
or in its immediate neighborhood ; and then develope into minute frondlets, consisting 
of two or three cells, the lowest of which contains endochrome, and acts as a mother- 
cell, while the uppermost becomes an antheridium in which spermatozoids are formed. 
After a time both the female-cell and the antheridium open at the summit ; the sper- 
matozoid is liberated and enters the aperture of the ovarian cell and fertilizes the 
enclosed nucleus ; from which there results the large, immoveable spore characteristic 
of the genus. The whole process is described and its various stages elaborately figured 
in Pringsheim’s memoir, republished in a French translation in An. Sc. Nat. 4th ser ., 
vol. 5, p>. 250, t. 15, to which I must refer for a fuller account. A previous memoir by 
the same author in An. Sc. Nat ., vol. 3, describes the fertilization of the spores of 
Vaucheria by an analogous process. Various memoirs have also recently appeared by 
Thuret, and by Derbes and Soliere, describing the process of the fertilization of the 
spores, and the development of the frond in other classes of the Algae ; and from the 
large number of species which have been investigated by these excellent observers, we 
may perhaps be warranted in drawing the general inference, that a process of fertiliza- 
tion, by two opposing sexes, exists in all the Algae. It certainly exists in the Melano- 
sperms, Rhodosperms, and in many of the inferior Chlorosperms. There is much variety, 
however, in the appearance of the antheridia in different classes ; in some no spermato- 
zoids have yet been discovered, in others they are of considerable size, and very active 
and well formed. In some cases each spore is separately fertilized ; in others it is a 
body which afterwards developes spores. One important observation has been made by 
Pringsheim which is specially interesting from its bearing on the disputed question of 
the origin of the embryonic vesicle in the higher plants, namely, that in no instance has 
he observed any growth to proceed from the spermatozoid, but that its function seems 
to have been performed when its contents have mixed with those of the nucleus ; the 
spermatozoid itself being wholly absorbed and dissolved in the mass. 
Much still remains to be done in tracing the development of these Algae, more 
especially in studying the transformations which many of them undergo. Very many 
have two or three different modes of re-producing the species, as by self-division, by 
zoospores or gemmae, and by properly fertilized spores ; and the individuals resulting 
from these various modes of growth are not always similar. Thus there is in many an 
“ alternation of generations,” to be studied, such as has been noticed among lower 
animals ; and probably when the subject has been properly worked out, a large number, 
not only of species, but of genera, especially among the fresh water kinds, must be 
erased from our lists. It now appears probable to Pringsheim that many of the minute 
