738 
AZOLLA FILICULOIDES LAM. 
at Woodbastwick and divided into three series: — (l) Sun-dried 
and exposed to the air for twenty-four hours. (2) Dried on 
blotting paper for a few minutes. (3) Untreated. All three 
series yielded visible sporophytes in sixteen days. 
By the indulgence of Professor J. H. Priestley and the 
Senate, I have been enabled to continue the study of Azolla in 
the Botanical Laboratory of Leeds University. Serial sections 
have been made in order to follow the development of the 
prothallium and sporophyte, but the primary object was to 
ascertain the condition of the spores which, while capable of 
germinating, lie dormant and accumulate at Woodbastwick. 
The vast number present in this particular ditch may be gauged 
from a sample of mud taken in June, 1913, a tablespoonful of 
which yielded twenty macrospores. The material dealt with 
consisted of (a) residual mud in cultivation since October, 
1912, from which many plants had developed ; ( b ) mud collected 
and air-dried in October, 1913. On January 27th, 1914, these 
were placed in a glass house having an average temperature of 
60° F. (40° — 70° range), spores having first been taken from 
each for microscopic examination, (a) Showed no signs of 
vitality ; many of the spores were discoloured and sections 
showed them to be deficient in protoplasm, or quite empty. 
None developed in the culture tank. Under the same cultural 
conditions (6) produced visible sporophytes in sixteen days, 
and by March 18th thirty had emerged, the largest then having 
seven leaves. Spores from the dried mud, soaked for two days 
and sectioned, showed variable states of vitality ; some were 
healthy and full of protoplasm, others were discoloured and 
empty. On March 18th the residual mud yielded 115 spores 
with the conical caps in some cases closely attached, in others 
more or less displaced by the emergent pear-shaped bodies. 
Dissection of a small number showed that some were dead and 
discoloured, collapsing on pressure, and with scanty or no 
protoplasm. From superficial examination with a lens it was 
estimated that 30 % were capable of germination. Allowing 
for those previously developed, the original gathering contained 
about 55 % dead and 45 % living macrospores. 
