DEDIFFERENTIATION IN PEROPHORA 6638 
exhibited a phenomenon characteristic of Amaroucium—the 
protrusion of the pharynx from the test and its subsequent 
decay, the abdomen and post-abdomen remaining and dedif- 
ferentiating. The small individuals underwent a_ process 
obviously analogous to the dedifferentiation of Clavellina. 
They shrank in size and decreased in transparency. ‘The 
siphons at first remained attached to the test (unlike Clavellina), 
but later became completely detached. The pharyngeal 
region, as in all other reducing Ascidians, shrank much more 
than the rest, and finally a stage was reached in which the 
two main portions of the body were still distinguishable, 
separated by a slight constriction ; the general shape was thus 
that of a constricted sausage ; the organism was completely 
opaque, the colour being white with patches of red. (Certain 
organs of the normal zooid show this same red colour.) A 
curious feature was the frequent formation of clear projections 
of the test. These were generally stalked, and spheroidal or 
ellipsoidal, like bubbles or bladders. Healthy-looking test- 
cells could be seen in them. Very frequently new buds would 
be formed from the dedifferentiating zooids during the process 
of reduction. These would attain a certain degree of organiza- 
tion, but would not usually reach full development unless the 
piece were replaced in clean and regularly-changed water. 
This replacement in clean water, however, did not lead to the 
redifferentiation of the reduced original zooids. 
After seven to twenty days, when it had become evident that 
it was not possible to obtain the extreme stages of dedifferentia- 
tion seen in Clavellina, the surviving pieces were all placed under 
gauze in the circulation. When examined twenty-nine days 
after the inception cf the experiment it was found that a few 
had remained in approximately the same condition in which 
they had been placed in the circulation. More than half, 
however, while the original zooids had not redifferentiated, 
had given rise to new zooids, usually in one or two clusters of 
four to six zooids each. 
It thus becomes clear that Amaroucium shows yet a third 
type of dedifferentiation. The specialized method of forming 
