360 BOTANICAL GAZETTE [NOVEMBER 
Contemporaneous with the development of the group of pro- 
carps is the luxuriant growth of the whorl of short filaments 
from the segment of the procarpic branch just below the terminal 
segment. Some of these filaments become the large bracts that 
surround the mature cystocarp. They develop, as do all the 
structures of the frond, by growth from the terminal cells of fila- 
ments, and jigs. 5, 6, and zo illustrate the appearance of the 
chief stages. 
The typical number of procarps in the group is five, but 
instances of over or under production are not infrequent. In 
cases where the number is less than usual the second procarp of 
the pair is most likely to be absent, and occasionally one or both 
of the lateral procarps may be suppressed. Examples of over 
production are more frequent, and perhaps the most common 
instance is that in which a pair of procarps is found in place of 
the inner procarp of the group. Sometimes an’ additional pro- 
carp may be attached to the basal cell of the pair. None of 
these irregularities transgress the law of development that we 
have advanced, for in all cases the procarps are short branches, 
the terminal cells of which have become specialized into tricho- 
gynes. 
‘\ 
MINUTE STRUCTURE OF THE PROCARPS. 
Now that we understand something of the development and 
arrangement of the procarps in the group, we are in a position 
to consider the minute structure of the cells. The material had 
been well fixed in chromic acid, and proved excellent for the 
. @€Xamination, 
In the first place, we may refer to the peculiar str 
the cell-wall often found around the young procarps, which is 
different from anything that the writer has ever seen described. 
Unlike the cell-walls on other portions of the frond, which are 
perfectly homogeneous in structure, the wall is 
differentiated into an inner and an outer zone. if: 4 may » 
taken as an excellent illustration of this peculiarity. This spe 
men had been stained with Bohmer’s hematoxylin, 
ucture of 
