Davis. — The Fertilization of B air acho sperm u m. 59 
gradual narrowing of this strand. It is as if the masses of 
protoplasm in the two structures were slowly contracting ; 
and to judge from appearances this seems to be actually the 
case. As the strand becomes thinner the space necessarily 
left between it and the cell-wall at the base of the trichogyne 
is filled up by a deposit of a substance exactly similar in 
colour and density to the cell-wall itself. This deposit is 
shown in Fig. 7, where the connecting strand is much thinner 
than in Fig. 6. Finally the thin strand is drawn apart and 
the ends of the two separated masses of protoplasm round 
themselves off, one becoming the lower end of the separated 
trichogyne, the other the upper end of the carpogonium. 
A light streak that is frequently seen running through the 
deposit between the carpogonium and trichogyne (see Fig. 8), 
may indicate the presence of the cavity in which the connect- 
ing strand originally lay. But this appearance is but 
transitory ; and such a cavity, if it exists at all, is quickly 
closed up, so that the whole intervening portion of the structure 
between the protoplasm of the trichogyne and that of the 
carpogonium consists of this substance exactly similar to the 
cell-wall. 
It will be seen that the deposit between the trichogyne and 
carpogonium is not exactly of the nature of a plug placed into 
an opening between the two, but it is an addition on the 
inside to the thickness of the cell-wall which is deposited 
as gradually as the separation of the protoplasm takes place, 
and follows the latter process very closely. That the separa- 
tion takes place gradually is shown by the great variety of 
stages which one is able to find without difficulty. The 
writer has endeavoured to watch the operation in living 
material, and his attention has never been attracted to any 
movement of the protoplasm either during the process of 
fusion of the antherozoid or separation of the trichogyne from 
the carpogonium. 
Concerning the nature of the substance deposited between 
the trichogyne and carpogonium, the writer can say but little. 
It did not give a clear cellulose-test with iodine and sulphuric 
