640 Lewis.— The Life History of Griffithsia Bornetiana. 
like the sexual individuals, sometimes produces reproductive organs when 
consisting of but 10-20 cells and having a height of less than half a 
centimetre. 
One plant was seen in which a few antheridial branches occurred, 
while the majority of the filaments bore numerous procarps and cystocarps. 
In another case, most of the branches produced antheridia, but a con- 
siderable number bore at the nodes rings of cells resembling in all particulars 
tetraspore-mother-cells, with the involucral rays characteristic of the tetra- 
sporic sorus. These tetraspore-like structures are described in detail on 
P . 671. 
Griffithsia Bornetiana becomes conspicuous at Wood’s Hole in the 
first half of July, and grows rapidly until it reaches its maximum develop- 
ment about the first week in August. Towards the middle of August the 
plants of all ages cease to produce new branches, and slowly become 
disorganized, losing their rich pink colour, and becoming easily detached 
from the substratum. At this season great quantities are washed up 
on exposed points like Nobska Point at Wood’s Hole. After being torn 
loose from their fastenings, the plants float about in the water for days 
or even weeks, continuing to produce spores which were shown by experi- 
ment to be capable of germination. At this season, the tetrasporic plants 
frequently show a very robust habit, forming spherical masses upwards 
of 15 centimetres in diameter. 
The spores develop quite rapidly in the open. Bits of cotton cloth, 
tied to piles near mature plants, showed in two weeks’ time sexual plants 
with ripe antheridia and carpospores, and tetrasporic plants with mature 
spores. The largest of these plants showed eight orders of branching, and 
consisted of as many as 500 cells. 
A noteworthy fact about the occurrence of the various forms is that 
tetrasporic plants are always more abundant, as well as on an average larger 
than sexual plants. During the first two weeks of August, 1907, more than 
500 plants were collected, care being taken to collect every plant seen, and 
not to select the larger specimens. On one occasion 352 individuals were 
brought into the laboratory and sorted carefully. Of these 321 were found 
to be tetrasporic, 15 cystocarpic, and 16 antheridial. At another time 
more than 200 plants showed about the same relative proportions. In other 
words, there is on an average an equal number of antheridial and cystocarpic 
plants, and for each sexual plant about ten tetrasporic ones. An exact 
count was not kept of plants collected earlier in the season, but there seems 
to be no doubt that tetrasporic plants greatly predominate in number at all 
seasons. 
The same relations are shown quite strikingly by Champia parvula and 
Chondria tenuissima , at Wood’s Hole, and will probably be found to obtain 
in many other red algae. Similar numerical preponderance of tetrasporic 
