Davis.— The Fertilization of Batrackospermum . 73 
antherozoid, nothing more remarkable ever happened than 
its passage into the upper portion of the trichogyne. The 
cytoplasmic fusion of an antherozoid with the trichogyne 
cannot be considered as a sexual process in the usually 
accepted meaning of the expression, for the essential charac- 
teristic of the process is considered to be the intimate union 
of the substances of sexual nuclei. However, the isolation- 
experiments and all observations seem to prove that the 
union of an antherozoid with the trichogyne is necessary 
for all farther development of the procarp, and also that it 
is cytoplasmic fusion between the two which is the exciting 
cause of the separation of the trichogyne from the carpo- 
gonium. It is hard to suggest what other term than 
fertilization can be used to describe this act, because all 
the subsequent changes are apparently the direct sequence 
of the influence of an antherozoid upon the trichogyne. 
What then can be the meaning of these curious conditions ? 
There seem to the writer only two possibilities open : — 
(1) Perhaps the conditions of sexual reproduction among 
the lower plants are such that the fusion of the nuclei of 
the two sexual cells is not absolutely necessary : possibly 
a stimulus of some sort, the result of cytoplasmic fusion, is 
all that is required. Such a stimulus could readily be con- 
ducted from one cell to the other by the wide strand 
of protoplasm between the trichogyne and carpogonium. 
(2) The second possibility is that the present condition is 
a much modified form of what was once a true sexual process, 
the plant having lost the most important feature of the 
process (the union of sexual nuclei), but the stimulus of 
cytoplasmic fusion being still required : that is, the plant 
is tending towards a condition of apogamy. The present 
trichogyne may then be a modification of some ancestral 
type of structure when the procarp resembled that of Nemalion 
at the present time. 
As we know very little about the fate of nuclei in the 
sexual cells of the lower Cryptogams during the process of 
fertilization, it is quite impossible to draw any analogies. 
