Grinnellia americana , Harv . 17 
formed in the neck of the trichogyne. Shortly after this, 
zoogloea-bacteria collect about the distal end of the trichogyne 
and cause its rapid disintegration (Fig. 14 b). This shows the 
evanescent character of the organ, which decomposes and 
falls away in a short time after receiving the contents of the 
fusing antherozoid. 
As there is no indication of a conjugating tube connecting 
the carpogonium to the large auxiliary cell which supports 
the procarpic branch, and as there are open pores connect- 
ing the cells of the procarpium, it seems evident that, with 
the substitution of pores for pits, Bornet’s explanation of the 
method of propagating the fertilizing influence from the car- 
pogonium to the cell which develops the sporiferous tissue 
must be accepted in this Alga. 
Very soon after the fertilizing contents of the carpogonium 
have been transmitted to the auxiliary cell (the large thallus- 
cell which supports the procarpic branch), it begins an active 
growth. It increases in size, develops a very thick cellulose 
cell-wall, and becomes gorged with dense, yellowish, proto- 
plasmic contents. A similar and accompanying phenomenon 
is observed to occur in the four large auxiliary cells which 
immediately surround this supporting cell of the procarp and 
are found in the plane of the frond (Fig. 16). 
These cells are nucleated, have the same general position 
with reference to one another (Fig. 25), and form a distinctive 
group in all young cystocarps. 
In their study of Gracilaria , Bornet and Thuret refer to 
a group of cells in the basal region of the fruiting body 
which resemble this group in Grinnellia. In a subsequent 
investigation of the procarpium and fruit of Gracilaria , 
Mr. Johnson mentions the same cells and considers them 
a part of the procarp. In Grinnellia they are auxiliary cells 
of which the central one develops the sporiferous tissue 
subsequently to receiving the fertilizing influence of the 
carpogonium. 
The developmental changes in the young cystocarp are 
very rapid from this period. The central cell of this group, 
C 
