248 STuDIES IN GENERAL PHYSIOLOGY 
This time I distributed the individual animals of a colony of 
Tubulariz into different vessels, containing 10, 20, 50, 100, 
and 200 c.c. of sea-water. Each vessel contained six Tubu- 
larian stems, the roots and polyps of which had been ampu- 
tated at the beginning of the experiment. The vessels were 
relatively flat, and only lightly covered with a glass plate to 
shut out particles of dust that might be carried in through 
the air. Oxygen could therefore readily reach the sea-water. 
The first polyps were formed after three days—five in each 
of the vessels containing 100 and 200 c.c. of sea-water, and 
two in each of the others. Two days later all of the animals 
had formed new polyps. The inhibition of regeneration was 
therefore only slight in the vessels containing but a small 
amount of sea-water. On the eighth day after the beginning 
of the experiment I measured the growth of the individual 
specimens, which was as follows: 
In 10 c.c. of Sea-Water In 200 c.c. of Sea-Water 
8.0 mm. 7.0mm. 
12.0 8.0 
6.5 13.0 
5.5 9.0 
7.0 10.0 
4.0 3.0 
Average 7.1mm. 8.3mm. 
I obtained about the same average values in the rest 
of the vessels. Ten c.c. of sea-water therefore contain suffi- 
cient inorganic material for normal regeneration and normal 
growth, and variations in the quantity of sea-water above 
this limit have no effect upon these processes. I have not 
made experiments with less than 10 c.c., as these barely 
suffice to cover the Tubularian stems. The result of these 
experiments is free from the complication which enters 
into Semper’s experiments, in which the animals devoured 
an uncontrolled (and possibly uncontrollable) amount of 
vegetable food. 
Digitized by Microsoft® 
