194 THE AMERICAN NATURALIST. | [Vor. XXXVI. 
Nutritive polyps cut from the hydrorhiza were grafted by 
Peebles in pairs, either by their oral ends (after removing both 
heads) or at the aboral ends (with both heads attached), or the 
aboral end of one individual was grafted-to the oral end of 
another, from which the head had been removed. In all cases 
the line of union between the two components was ‘soon 
effaced, the digestive cavities became continuous, and a com- 
plete union seemed to be effected. In all the experiments in 
grafting ‘nutritive polyps, nutritive heads were regenerated at 
one or at both ends, and often also in the region of the graft. 
_ The union of different kinds of individuals was also successfully 
accomplished as follows: The aboral end of a nutritive polyp 
was grafted to the aboral end of a protective polyp,— the 
direction of the two components being thus reversed. After 
a few hours the nutritive head was removed, leaving a portion 
of its stalk attached to the aboral end of the protective polyp. 
The head which regenerated at the free cut surface showed 
markedly the characteristics of the nutritive individual and 
did not seem to be in the least affected by union with the 
protective polyp. Similar grafts were made with nutritive 
and reproductive polyps, followed by a removal of the repro- 
ductive head. Here, again, the regeneration of a reproductive 
head at the end of the stalk showed no modification due to 
the union with a nutritive polyp. 
The results of these experiments by Peebles suggested the 
following questions: first, Would the fixation by means of 
stolons of one of the components of the graft alter the result? 
second, Would the kind of regeneration that took place be 
affected by the relative orientation (with respect to the polar- 
ity) of the pieces? With these questions in mind, I carried 
out the following series of experiments at the Marine Biolog- 
ical Laboratory during a few weeks in July and August, 1901. 
Both Hydractinia and Podocoryne were used, and the method 
of grafting was similar to that employed by Peebles. It was 
found to be of importance to use fresh material since that 
kept for several days in the aquarium: regenerated more 
sd and less bir) than material’ | just brought in. A 
few 
repeated 
n Lu 

