68 Davis . — The Fertilization of Batrachospermum. 
less clearly differentiated portion of the protoplasm, having 
a greenish tint : in young specimens this body may be readily 
traced back into the carpogonium, where it joins the chroma- 
tophore of that structure. The antherozoids of this plant are 
unusually large, and are somewhat peculiar in that the pro- 
toplasm is frequently entirely confined to a rather thin 
layer next the cell-wall, the central portion being occupied 
by a large cavity or vacuole. Half-developed antherozoids 
contain a very distinct chromatophore. The colour and 
structure of this body gradually change as the antherozoid 
matures, in a manner precisely similar to the antherozoids of 
B. monitiforme ; i. e. the green tint becomes fainter and the 
structure granular and less definite in outline. 
The separation of the contents of the trichogyne from the 
carpogonium takes place in exactly the same manner as in 
the two other plants. The area of the point of fusion between 
the antherozoid and trichogyne may be very small to accom- 
plish the fertilization of the carpogonium (see Figs. 35, 36, 
and 37). The position of the nucleus in the trichogyne is 
apparently not materially affected by the process of fusion. 
The nucleus of the antherozoid is very irregular in its 
situation, and one finds many instances where its position is 
remote from the point of fusion, as in Fig. 33 ; but it is often 
very near this point (Fig. 34). The nucleus of the antherozoid 
frequently passes into the trichogyne, but no indications were 
observed that it ever moved far down into that structure. 
Fig. 33 shows a particularly interesting case in which, if one 
may judge by the position of the granular protoplasm in the 
upper portion of the trichogyne, the movement of the cyto- 
plasm was into the antherozoid rather than from it. Fig. 35 
illustrates a type of trichogyne with a prolonged upper portion 
in which the nucleus was situated : but one also finds examples 
in which the nucleus lies below the middle portion of the cell. 
Nuclear fragmentation takes place in the cells of the 
antherozoid and trichogyne as these structures grow old. 
Some of the figures illustrate this phenomenon : thus Figs. 
35 and 36 show fragmentation in the antherozoid, and 
