YELLOW-BROWN CELLS OF CONVOLUYTA PARADOXA. 469 
proteid material to the animal, the results of the second mode 
of experimentation render highly probable. 
Here, in heu of determining the effect of uric acid on the 
life of algal ceil and animal, its influence on egg-laying was 
investigated. The results of these experiments are summa- 
rised in Table Il. In the first experiment of this series 
(started August 21st), five lots, each of twelve animals, were 
placed under the conditions indicated in columns 1—5 of the 
Table. 
As the numbers in these columns show, but one clutch of 
egos was laid in “ filtered sea-water, light,” one in “ filtered 
sea-water, dark,” none in “dark, weed” (column 5), four in 
“light, weed”? (column 3), and six in “filtered, hght, uric, 
and potassium nitrate” (column 2). 
The next experiment (August 28th) shows that uric acid 
alone suffices to induce the production of eggs. For, whereas 
in “filtered sea-water, light” only eight clutches (column 1), 
and these containing but few eggs, were produced by fifty 
animals; seventeen clutches (column 2), with larger numbers 
of eggs, were laid by an equal number of animals kept in 
filtered sea-water in the hght with uric acid. 
The third experiment shows that nitrogen in the form of 
potassium nitrate is also efficacious in inducing egg-laying 
(Table II, 2b). 
The total number of egg-clutches produced in these three 
experiments are:—in “filtered sea-water, light,” 9 ; in “filtered 
sea-water, light, and added nitrogen” (uric acid, potassium 
nitrate, or both), 27. 
These results would appear to prove that during the later 
stages of egg-development, when reserves are finding their 
way from animal to egg, a considerable portion of these 
reserves is obtained by the animal from the yellow-brown 
cells. ‘The small number of egg-clutches laid in filtered 
water in the light indicates that the reserves of the animal 
tissues do not suffice to supply the eggs with material for 
their full development. It is noteworthy in this connection 
that, as before stated, the granular substance of the refrac- 
