DEDIFFERENTIATION IN PEROPHORA 695 
Fig. 2 (x 80).—a. Immature zooid on day of operation. b. The same, 
perfect, after three days. The stolon has been much reduced both in 
length and breadth. A small bud had formed and been absorbed. c. After 
five days. Further reduction of the right end of stolon; zooid in first 
stage of reduction, which has led to a slight dilatation of the left end of 
the stolon. d. Stolon-tip from a similar system after three days, showing 
shrunken appearance. 
Fig. 3 (x 25).—a. A system on the day of operation. 6. The same 
three days later. Zooid actively functional, stolon much drained in all 
dimensions. 
Fig. 4.—Maintenance of bud following resorption of first zooid. 
a.(x80). Original zooid in stage 4 of reduction, after two days. Stolon 
healthy. 6. (80). After three days. Stage 4, but smaller; meanwhile 
a bud had formed to the left of the zooid, and by now was 50 per cent. 
larger in diameter than the zooid. c. (x40). After five days the zooid 
had disappeared. The remains of its test is seen. The right part of the 
stolon, to the right of the bud, has also been resorbed, and resorption is 
beginning in the other portion, as shown by the extent of its test. 
d., e. (x40). After seven days. In d. the tip of the stolon is shown 
contracted, in e. expanded with blood. jf. After twelve days. The stolon 
has almost disappeared. The zooid is practically unchanged in size or 
development. , 
Figs. 5-15.—Resorption of zooids and growth of stolons. 
Fig. 5 (x 25).—Stolon-growth. a. A system on the day of operation. 
b. The same, but stolon only ; four days later. The zooid was in stage 2 
of reduction. A bud is seen on one stoion-branch. Note the test bridging 
concavities of the stolon. 
Fig. 6 (x 40).—Karly stages of resorption. a. After two days. Zooid 
just reaching stage 3. The exhalant siphon is still slightly attached to 
the test. Faint traces of gills visible. The stolon-branch B and the tip 
of a represent new growth. 6. Eight and a half hours later. The zooid is 
in stage 3-4, and has shrunk considerably ; B has grown. 
Fig. 7 ( x 64).—Zooid in stage 3-4 of reduction, showing heart and traces 
of inhalant siphon and stomach ; note the double stolon-connexion. 
Fig. 8 ( x 64).—Zooid in stage 4 of reduction. The heart is seen end on. 
Fig. 9 (x 64).—Later stages of reduction. a. Zooid in stage 4, after 
two days ; ectoderm in places cubical. A stolon outgrowth had occurred. 
b. The same, ten hours later (test omitted) ; further shrinkage. Ectoderm 
all cuboidal. c. Fourteen hours later (test omitted); further shrinkage. 
A new stolon outgrowth has occurred. d. Forty-eight hours later (five 
days in all). It is now in stage 6 (after four days it had reached stage 5). 
The pale ovoid is probably the remains of the stomach. Note the slight 
reduction of the test. e. Twenty-four hours later (six days). Zooid por- 
tion smaller than stolon-connexion, 
