- 66 - 
the sperm cells, has been differentiated from the outer single layer of 
sterile cells which form the wall of the antheridium (Figs. 13 and 14). 
Fig. 15 shows what appears to be a mature antheridium, the central 
space being occupied by many sperm cells. Thus it would seem that 
the antheridia may be fully formed by the latter part of April. 
By means of the division of cells adjacent to the young antherid- 
ium it soon becomes surrounded by a partition and each becomes 
sunk in a little cavity or pocket (Figs. 11, 13, 14, 15). 
On April 28, more material was collected from the same place. 
The young shoots showed considerable growth in a week’s time. 
Again there was a great difference to be seen between the plants 
growing close to the water and those on the drier bank a few feet 
away. The former were much larger in size and more rank in 
growth, while the latter were small in size and thin in substance. 
The papilla-like antheridia showed plainly. All* the capsules had 
opened, but the stems surmounted by the tuft of elaters were still 
standing. Sections through this material showed no special dif- 
ference from that gathered on April 21, so no figure is given. 
. May 6 was the next collecting day, and this time another locality 
was visited, where the plants were growing at the river’s edge. These 
plants showed a marked increase in size over the preceding, and were 
very rank in growth and bright green in color. Sections of this ma- 
terial showed no marked advance over that gathered earlier, only 
there was a greater proportion of the more mature antheridia and 
fewer of the early stages were to be found. 
[to be continued.] 
EXPLANATION OF FIGURES 
These drawings were made with a Bausch and Lomb microscope, 
using ^ and ^ objectives, and 1 inch and ^ inch eyepieces. 
The sections were four or five microns in thickness. 
Figs. 8 — 31 were stained with Delafield’s haematoxylin. 
Figs. 31 — 51 were stained with the saffranin gentian violet and Orange 
G combinations. 
EXPLANATION OF PLATE VIII 
Fig. 2. a, b, c, d, e. New thalli springing out from edge of old 
plants, collected April 21. ci , di , ei . Old plants. 
Fig. 2. f. Characteristic shape of thallus, June 28. 
Fig. 3. a, b, c. Varying shapes of thallus, July 4. ai , ci . Old plants. 
Fig. 4. a, b, c, d, e f. Different shapes of plants, Aug. 16. ci . Old 
plant, e & f. show position and appearance of young sporo- 
gonium at this time with involucre dissected away. 
Fig. 5. Thallus collected Aug. 18, shows forking tendency when no 
surrounding plants interfere with growth. 
Fig. 6, a, b, c. Collected Aug. 6. 
6, a. Characteristic shape growing on wet leaves near the 
water. 
