No. 423:] HYDRACTINIA AND. PODOCQR YNE. 195 
and similar. results obtained, although most: of the grafts were 
made. by joining-the-aboral end ofa reproductive polyp to the 
oral end. of a nutritive stalk, the head of the latter having been 
previously removed. .In this way. the direction of the two 
components was the same, instead.of reversed, as in Peebles’s 
experiments. |The pieces were allowed to remain. undisturbed 
for a short time after grafting, or until, the tissues hàd become 
united, so that the reproductive head could be cut off without 
danger of separating the grafted pieces, Better results seemed 
to be obtained. if the head were removed 
within a few: hours after union, so that 
the process of regeneration started in the 
first night after the graft had been made, 
although satisfactory results were sometimes 
obtained when the cut was made on the 
second day. Fig. 1 represents a typical 
experiment of this kind. -An immature Fic.:— x45. Theaboral 
reproductive polyp (7) was selected and ee ee eee 
grafted at its abóral end.to- tbe oral end.. wagafted:to:the oral 
end of a nutritive stalk 
of a nutritive stalk (z.) from which the head - (4) August 3. A few 
had been removed, The tissues joined, and 
a few hours later the reproductive head was was cut off, as indicated 
removed, leaving the two components Of ` next day a reproductive 
nearly equal size. Within twenty-four hours 
a complete reproductive head had regener- reproductive stalk. 
ated (rh.), which showed no modification due (Dawn Aususts) De 
to the Wise of the stalk of the nutritive oral end of each irdi- 
polyp. 
When the union of the two soliponeets was incomplete and 
a part of the cut surface of the nutritive stalk was exposed 
at the side, tentacles or a whole nutritive head developed at 
this place, as shown in Figs. 2, 3, and 4, zz. This occurred 
frequently, as the nutritive polyps are often much larger than 
the reproductive polyps, and the latter, unable to cover the 
whole cut surface, unite with the nutritive only at one side. 
This did not prevent.the body cavities of the two. eens 
from becoming continuous. The portion. of the ‘re cti 
stalk (7.) used in the experiment shon, È in Pe 2 was s taken 



