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The co-existence of the two extreme forms in one pool 
suggests their independence as distinct varieties, but a 
consideration of the proportional representation of these 
forms throughout the space of a whole year has led to the 
conclusion that the narrow form with confluent sporangia 
and many mucilage hairs is that form of the species in which 
it survives unfavourable conditions. This form is therefore 
characteristic of the winter plants and also of those which, 
_ in the summer, inhabit the less favourable zones of the 
littoral region. The existence of the two forms, side by 
side in spring is due to the fact that individuals of the 
winter flora persist into the spring season, but their 
progeny achieve the greater stature of the summer form 
in response to the more favourable conditions of tempera- 
- ture and illumination, that govern their germination at a 
period when the sporelings are most sensitive to the 
factors of illumination and temperature. 
From the foregoing it is clear that AspPerococcus fistulosus 
is not an annual, as many algologists have considered but 
is represented throughout the year. Its presence on the 
shore is maintained by a succession of individuals each 
with a life-span of a few weeks’ duration. Changing 
physiological conditions of the environment will affect the 
sensitive sporelings and thus give rise to successive crops 
whose morphological features vary with the seasons. 
That this does not represent the whole matter is made 
clear by comparison with other areas. | Professor Kylin 
in his ‘‘ Studien tiber die Algenflora der schwedischen 
Westkiiste ’’ refers to two forms of Asperococcus echinatus, 
namely Lf’. typica and F. villosa, distinguished from one 
another by the extreme hairiness and by the confluence of 
the sori of the latter compared with the scarcity of hairs 
and clearly distinct sori of Ff. typica. FF. villosa is also 
smaller in stature than I’. typica. In many stations the 
length of F’. villosa plants lies between 5 and 10 cms., but 
