DEDIFFERENTIATION IN PEROPHORA 661 
the stclon was dilated by the blood-pressure, the flattened 
ectoderm cells becoming still more flattened. The test also 
underwent passive dilatation. 
However, even when the heart has ceased to beat, the stolon 
may be quite turgescent, and the ectoderm cells flattened, not 
cuboidal. Fullest turgescence, however, is thus only to be 
expected when the circulation is active and when the ecto- 
derm cells are healthy. 
[t may be mentioned that the first step in dedifferentiation 
may be regarded usually as a diminution of tone (turgescence). 
(}) Growing-points of Stolon.—At the tips of 
growing stolons the ectoderm is usually columnar (fig. 26) 
and the lumen generally filled with a dense mass of cells, 
into which the circulation does not penetrate. Sometimes, 
as in fig. 27, there is an increase in the number of green cells 
as We pass away from the tip. Often a layer of blood-cells will 
become attached to the walls of the stclon over a considerable 
distance, giving it an opaque appearance, though circulation 
continues internally. 
(c) Lateral Outgrowths of Stolon.—Some lateral 
outgrowths, as in fig. 25, were occasionally seen. They did 
not represent rudimentary branches. Their meaning and origin 
is obscure. 
(dq) Attachment of Stolons.—The stolons will usually 
attach themselves to the substratum. This I have seen 
accomplished within three and a half hours. 
(ec) Bud -formation.— When medium-sized zooids 
attached to stolons of fairly large size were employed, buds 
were often formed from the stolon when dedifferentiation 
began in the zooid. Sometimes two buds or more might 
form. Buds may form at either or both ends of a piece of 
stolon. Resorption might occur at any stage in the develop- 
ment of the zooid from the earliest bud up to half-grown 
individuals. 
({) Penetration of Zooids by Stolon Branches.— 
An individual was seen in which apparently a branch of the 
stolon had grown up inside the test of the stolon-connexion and 
