1896. ] Development of Champia. 113 
quently several of them but there may be only one. They 
are exactly similar to the thallus cell, bearing the procarpic 
branch, in the appearance of their cell contents, and we can 
only identify the latter by its attachment to the procarpic 
branch on the outside and asa rule to an internal filament 
on the inside of the frond. 
Coincident with the gradual change in the character of the 
cell-contents which precedes the differentiation of the auxil- 
iary cells, a number of short filaments begin to grow up over 
the procarpic branch. The filaments arise from the thallus 
cells around the procarpic branch, meeting at a point above 
it, and form a sort of dome over that structure. This is the 
beginning of the wall of the cystocarp. In the early stages it 
is perfectly evident that these filaments arise from ordinary 
thallus cells which afterward become auxiliary cells. So the 
auxiliary cells are not special structures developed separately 
rom the vegetative tissue, but they are cells of the vegeta- 
tive tissue directly around the procarp that become modified 
* to their cell-contents in a manner quite similar to those of 
€ procarp. 
An examination of the figures will perhaps serve to make 
fi 
ms 8) it will be noticed that the thallus cells on each side of 
*ver towards the procarpic branch. These with other cells, 
Which are developed later, become the apical cells of a com- 
plex ‘ystem of branches that form the wall of the cystocarp. 
8: 9 is of a stage not very different from fig. 7. Here 
dj Wall of the cystocarp has begun to develop, but the con- 
itlons of the Procarpic cell, 4, and the thallus cell which 
reer it, 4, are not materially changed except that they are 
knee and their nuclei much more prominent. On the right 
‘ 4 side of the figure is an auxiliary cell, a, very similar in 
tem “france and structure to the thallus cell which bears : ad 
md of the pr ocarpic branch. Above the auxiliary cel 4 
to ch “t cell rather dense in contents which is probably abou 
nge into an auxiliary cell. ; h 
or} '8: Io illustrates a case in which the procarpic branc at 
tich, ly composed of two cells besides the carpogonium pee 
branch je. He thallus cell, ¢, which bears the procarp 
“2 is so cut that only a portion appears in this section- 
