16 
food material and protected by their underground position 
from the rigours of the unfavourable season. On the 
contrary, the whole of the plant is at all times exposed to 
the medium of sea-water and to the influences of physical 
forces affecting it. Some few algae do indeed inhabit 
situations where the rock surface is covered by sand or 
mud ;—for example, Rhodochorton Rothu, Enteromorpha 
compressa, etc., but in general the plants derive no special 
benefit from such a situation: on the contrary, movable 
sand is apt to imperil rather than safeguard algal life. 
Within a marine environment there are always some 
plants which retain their power of growth throughout 
the year. On the British coasts, for example, at all 
times of the year one can find sporelings of Fucus in 
various stages of development scattered over the littoral 
zone. Many of them have started life in positions where 
they will never succeed in establishing themselves as 
mature plants, but the frequency with which one 
encounters these hardy young plants well outside their 
normal fucoid zone, indicates the ease with which liberated 
Fucus eggs will germinate, and argues that the alternating 
climatic conditions of winter and summer on these coasts 
do not materially affect the growth of Fucoids and other 
algae indicated in the list of perennials. Tolerance of 
these plants for a wide range of fluctuation in environmental 
conditions renders them, as far as growth is concerned, 
more or less indifferent to the seasons. 
This conclusion is supported by the ease with which 
proliferation from basal parts takes place after removal 
of the upper part of the frond. One frequently sees 
evidence of this in the Fucus zones. New apices are 
readily regenerated and new branches produced matching 
their predecessors in stature and elegance. Nevertheless, 
this regenerative process is not capable of indefinite 
repetition The individual at last loses its vitality and 
