70 Davis . — The Fertilization of B atrachospermum. 
The following resume of the principal points of the paper 
had best precede the consideration of the literature, when each 
topic may be discussed in turn. 
I. The trichogyne is a cell, possessing a well-defined nucleus, 
and when young, a body that must be considered, at least 
morphologically, as a chromatophore. The chromatophore 
becomes less clear in outline and fainter in colour as the 
trichogyne develops, but traces of it may usually be found 
in the mature structure. 
II. The carpogoniunt is the cell situated directly below the 
trichogyne and connected with it by a strand of protoplasm. 
It contains a centrally-placed nucleus. 
III. The anther ozoids in an early stage of their development 
contain a body certainly derived from the chromatophore of 
the vegetative cells, and having a distinct green colour. As 
an antherozoid matures, this chromatophore-derivative changes 
greatly in appearance, its structure becoming granular and the 
colour fading until the antherozoid is practically colourless. 
The nucleus is usually situated in the layer of protoplasm 
near the cell-wall, the central portion as a rule containing 
a large vacuole. 
IV. The fertilization of the procarp is accomplished when 
the trichogyne becomes separated from the carpogonium. 
The process of separation consists of a gradual drawing apart 
of the cell-contents of the two structures until the connecting- 
strand becomes so thin that it breaks. The cavity left by 
the separation of the two masses of protoplasm is filled in by 
a deposit of a substance similar in character to the cell-wall. 
The exciting cause of the process of fertilization is the 
cytoplasmic fusion of one antherozoid with the contents of 
the trichogyne. The evidence to support this statement is 
of two kinds. First, as shown by isolation-experiments on 
living plants, the fusion of an antherozoid is necessary for the 
further development of the carpogonium. Second, it appears 
that the process of separation may take place when the point 
of union between antherozoid and trichogyne is very small, 
