226 SEA WEEDS 
carpogonial branch consists of four cells, and is 
formed, near the apex of a growing shoot, from one 
of the ordinary thallus cells. It curves backwards 
towards its point of origin and adjoins the basal cell 
from which the branch takes its rise. The tricho- 
gyne is also bent outwards, and penetrating the 
outer gelatinous coat of the thallus emerges into 
the open. Simultaneously with the formation of 
the carpogonial branch, the auxiliary cells are 
formed in the following manner. Two cells adjoin- 
ing the one which bears the carpogonial branch 
each segment off externally one cell in such fashion 
that the carpogonial branch lies between them. 
The parent cells of these two auxiliary cells are 
usually large thallus cells, but in no way distinct 
from the ordinary thallus cells. Sometimes both, 
sometimes one only is connected by a pore with the 
cell which bears the carpogonial branch. Though 
both of the auxiliary cells are apparently equally 
adapted for its function, only one of them is utilised, 
and it happens exceptionally that only one is 
actually produced. In most cases the fertilised 
carpogonium is directed towards the auxiliary cell 
destined to be used, and the latter is then rich 
in contents. Immediately after fertilisation the 
carpogonium fuses first with the cell of its branch 
next it, and eventually with all four cells of the 
carpogonial branch, while at the same time all 
increase in size, as well as the cell which bears the 
branch. The great cell arising by this fusion is 
then farther increased by union with the cell that 
bears it, and only one large nucleus is discernible for 
