450 FREDERICK KEEBLE. 
For example, the yellow-brown cells of animals caught on 
July 24th, 1907, contained numerous large fat-globules. 
Animals from this catch were transferred to filtered sea- 
water, and kept, some in darkness, others in the light. After 
four days (July 28th) the dark-kept animals contained no fat, 
whilst those kept in the light still contained fat-globules in 
their yellow-brown cells. 
It follows, therefore, that either the oil-globules are reserve 
substances formed from the products of the photosynthetic 
activity of the yellow-brown cells, or they are derived from 
the tissues of the animal. 
So little is known of the modes of nutrition of the lower 
aloze that the & priori objection to the latter interpretation 
is valueless. For it is based implicitly on the hypothesis of 
autotrophic nutrition of the algze in general. 
Kxperiments designed to determine this question seem at 
first sight to support the conclusion that the fat is derived 
from the animal tissues. If animals, whose yellow-brown 
cells contain fat, are placed in darkness, some in filtered sea- 
water, others in ordinary sea-water with seaweed from the 
Paradoxa zone, it is found that the fat disappears more rapidly 
from the animals kept in filtered sea-water than from those 
supplied with food. From this it might be concluded that 
new supplies of fat reach the yellow-brown cells from the 
digested products of the food taken in by the animal. 
Against this, however, is the fact that the disappearance of 
the fat from the yellow-brown cells of animals kept in dark- 
ness and supplied with seaweed and hence with food is only 
a matter of time. Kept under such conditions, although the 
animals continue to feed, the fat disappears from the algal 
cells, and finally these cells undergo degeneration. The right 
inference to be drawn, therefore, from the slower disappear- 
ance of fat from the yellow-brown cells of dark-fed animals 
would seem to be that the food ingested by the animal acts 
in some measure as a protection to the yellow-brown cells 
hence the reserves of food-material accumulated in these 
cells are not drawn upon by the animal so rapidly as is the 
