Howe: PHYCOLOGICAL STUDIES 507 
starch appears to increase at the expense of the chlorophyl. Some 
of the spores show a pronounced polarity, or perhaps it may be 
called a beginning of germination, while still in the sporangium, 
Thus, in the second spore from the right in FIGURE 21, the foot or 
base of the young plant is plainly manifest. Such basal parts have 
less chlorophyl and starch than the remainder of the spore. The 
membrane enclosing the spore is usually thin and delicate and often 
scarcely demonstrable. When the spores are well formed, there 
is a peculiar aggregation of granules at the apex of the sporangium 
(FIGURES 21, 24) and this appears to be followed soon by the 
rupturing of the sporangium wall in this region, forming a rather 
wide irregular opening. All the spores in any single sporangium 
seem to be discharged at about the same time, for the sporangia as 
found, with a few possible exceptions, are either empty or contain 
their full complement of spores. Very little is known of the 
history of the spores on leaving the sporangium. FIGURE I9 
shows a spore which had been caught at the mouth of the spor- 
angium and had evidently begun its extra-sporangial growth, form- 
ing an evident foot and the first ‘“bead”’ of a moniliform filament ; 
this was firm-walled and very brown. 
The large size of the spores (130-300 / X 66-120), their 
heavy load of starch, and their occasional development of an evi- 
dent foot while still in the sporangium, make it practically certain, 
in our opinion, that these bodies are not self-motile, 7. ¢., that they 
are aplanospores. Yet, the thinness of the surrounding membrane 
and the fact that none of the bodies has thus far been found ger- 
Minating on the surface of the thallus (if we except the captured 
one shown in FIGURE 19) have suggested the possibility of their 
being synzodspores. However, it is much more probable that we 
have to do with aplanospores, perhaps analogous to those which 
ccur in smaller size and larger number in Gomontia polyrhiza 
(Lagerh.) Born. & Flah. or to those which have been described as 
occurring singly in Vancheria hamata and V. geminata.” 
E. ON THE AMERICAN SPECIES OF AVRAINVILLEA 
In a former paper + we alluded to some of the difficulties in the 
Way of distinguishing species in the genus Avrainvillea and com- 
cd le a... 
* Waltz, J. Jahrb. Wiss. Bot. 5: 132, 133- 1866. 
T Bull. Torrey Club 32: 565-568, 586. 1905. 
