56 Davis. — The Fertilization of Ba trac ho sperm u m. 
as chromatophore-derivatives. We shall have occasion to 
speak of the future fate of this body after we have described 
the process of fertilization. 
We may now consider the structure and development of the 
antherozoids. In this species they are formed in groups at 
the ends of filaments towards the tips of the branches. Such 
a group is shown in Fig. 3, and in this case consists of three 
antherozoids, a , b, and c, in different stages of development. 
Perhaps the most interesting point in connexion with their 
development is the fact that the young antherozoids have 
a very distinctly outlined body in them that has the unmis- 
takable colour of the chromatophore of vegetative cells. The 
appearance of this body is shown in Fig. 3 a. As the anthero- 
zoid matures, a change takes place in its chromatophore 
similar to that in the chromatophore of the trichogyne. The 
colour fades, the homogeneous structure becomes granular, as 
is indicated in Fig. 3 b } and the chromatophore breaks up into 
many smaller bodies, which finally become practically colour- 
less, but nevertheless remain in the antherozoids as differen- 
tiated masses of protoplasm giving the granulate structure 
shown in Fig. 3 c . These bodies would be considered quite 
colourless by any one who had not studied their development, 
though they occasionally show traces of their original green 
tint. Each antherozoid contains a nucleus that is commonly 
situated in the layer of protoplasm that lies next the cell-wall 
(see Fig. 4). 
What, now, is the real nature of the trichogyne ? It starts 
as a process from the terminal cell of a branch, but at a very 
young stage a distinct nucleus is plainly recognizable in the 
developing structure. Thus in the young stage shown in 
Fig. 1, a nucleus is present in the swollen extension of the 
cell c. The extension develops into the trichogyne, the cell 
below (c) becoming the carpogonium. The nucleus in the 
trichogyne usually assumes a position near the middle portion 
of the structure, lying however in the protoplasm close to the 
cell-wall. But the position is not a fixed one ; sometimes the 
nucleus is found to be at the top of the trichogyne, and some- 
