4i 8 Os ter hout, — On the Life- History of 
gave the matter of fusion no special attention. These state- 
ments have been corrected by later investigation. Davis (’96) 
has recently questioned the sexuality of Batrachospermnm> 
but my own observations, not yet published, so far from con- 
firming his results, show conclusively that a true fertilization 
takes place. Wille (’94) has also been able to demonstrate 
fertilization in Nemalion. Until further and conclusive 
evidence to the contrary has been brought forward, we must 
assume that the cystocarp is the result of a sexual act. But, 
as De Bary (70) long ago pointed out, the cell from which it 
originates does not become morphologically separate from the 
mother-plant. In Mosses, Ferns and Flowering-plants, the 
sporophyte-generation begins with a cell which is morphologi- 
cally separate from the gametophyte on which it is borne. 
Too much stress need not be laid on morphological separation, 
since in the Phanerogams the mother-cell of the embryo-sac, 
which is generally assumed to be the starting-point of the 
female gametophyte-generation, shows no more morphological 
independence than the trichophore of the Fdorideae. The 
question cannot be decided until it has been determined at 
what point in the life-cycle the reduction to one half the 
number of chromosomes takes place. The general behaviour 
of the cystocarp points to the conclusion that an alternation 
of generations is really present. 
Whether this be really the case or not, it is interesting to 
notice how the development of the cystocarp finds a striking 
parallel in that of the sporophyte of Liverworts. In its most 
elementary form it consists almost entirely of sporogenous 
tissue ( Callithamnion ) like the sporocarp of Riccia. In its 
most highly developed form it consists of more or less 
sporogenous tissue borne on and nourished by a mass of sterile 
tissue (the f placenta 5 of Rhabdonia ), corresponding to the 
foot and columella of Anthoceros. Between these extremes 
numerous intermediate forms are present in both groups. 
Positive proof of the homology of the two structures is at 
present lacking, but the analogy, if it be nothing more, is 
most striking. 
