AZOLLA FILICULOIDES LAM. 
737 
Except when accidentally exposed to desiccation, they 
are water-logged and have a density greater than that of 
water. A careful watch has failed to reveal any detached 
spores floating in the Woodbastwick ditch, and experiment 
has shown that spores of both kinds sink unless first exposed 
to the air ; in fact, during any month of the year they may 
be collected from the mud bottom. It, however, seems not 
improbable that there may be a substratum of truth in 
Strasburger’s “ Schwimmkorper ” theory. A terrestrial state 
of the plant, possessing well -developed root hairs, has been 
seen, and it must frequently happen that fluctuation of water 
level exposes both fertile plants and shed spores. After such 
an exposure the spores may float for many days and acquire 
an increased range of transport. 
Writing from his experience of A. filiculoides in California, 
Campbell J states that The most prompt germination was 
found in material gathered in early autumn, which is probably 
the ordinary time for germination. Spores collected late in 
November germinated, but less promptly. In a few cases, 
within eleven days from the time that the spores were freed 
from the plants and placed in water, the young plants had 
already broken through the prothallium, and this was usually 
the case within two weeks.” 
In Norfolk, the attempt to follow spore development in the 
field having failed, spores were collected from the mud bottom 
at short intervals from October, 1912, and kept under observa- 
tion in a cold house. In April, 1913, a cluster was taken 
out for exhibition and remained in paper two days ; when 
restored to water the spores were dry and floated. On May 6 th, 
fifty of these had germinated, but those undried showed no 
change until a week later, and these latter continued to 
germinate irregularly throughout the summer. 
Spores collected on June 28th were air dried until July 4th. 
By August 1st, seventeen had developed cotyledons. 4 
On August 1st spores were collected from the mud bottom 
2 Ibid, p. 170. 
