Champia parvula , Harv. from the Carpospore. 351 
are secondary structures developed to strengthen the cortex. 
The usual view has been to consider the initial cells morpho- 
logically as the ends of the hyphae, and the cortex as a tissue 
developed from the hyphae. 
Longitudinal sections of young plants *36 mm. long were 
cut, which were without a trace of hyphae and of course with- 
out diaphragms, as the latter are developed from hyphae. 
Sections of plants *28 mm. long were also cut and these had 
both hyphae and diaphragms. 
The figures 14-18 tell the story of the development of the 
hyphae. Fig. 14 is an optical section of the fully segmented 
spore, shown in Fig. 8. Fig. 15 is a longitudinal section of 
a plant -20 mm. long, and it would probably appear in cross- 
section in about the stage of Fig. 12. The comparative length 
and breadth of the initial cells lettered x is shown. In Fig. 
16, which is a section of a plant -25 mm. long, we have the 
first beginnings of two hyphae : x and x 1 are the two initial 
cells, and just behind them may be seen the segments which 
have been cut off from them. Segments 1 1 , 2 1 , 3 1 have each 
been divided by a wall parallel to the surface of the cortex, 
cutting off the cells of the hyphae lettered h 1 , h 3 . Seg- 
ment 1 on the left-hand side of the figure has not divided, 
but from segment 2 a hypha ( h ) has started. It is worth 
noticing that the segments i 1 , 2 1 , and 3 1 and 1 and 2 are part 
of the same tissue, which extends to the base of the plant, and 
that the cells below them have no connection with the 
hyphae. From the appearance of the ends of the hyphae 
it is probable that they creep down a little on the inside of 
the frond, see Figs. 16 and 17. 
Fig. 17 is a figure of a longitudinal section through a plant 
•32 mm. long. The first diaphragm (lettered d) has been 
formed, but the section was cut a little obliquely and does not 
show the relation of the cells of the hyphae to the cortex as 
well as does Fig. 18. It is interesting, however, on account 
of the two hyphae lettered h , both of which seem to have 
grown down along the inside of the frond from the apex. 
The series of four transverse sections shown in Fig. 13 are 
