CHANDLER FULTON 289 



through the tissue of the colony to the tips of the stolons. The waves 

 are rhythmic, though very slow, occurring about two or three times 

 an hour in a resting colony. The rate of peristalsis jumps threefold 

 on feeding, to a frequency of about eight times an hour, and 

 then declines back to the resting rate. 



The most striking feature of this peristalsis is that it is sychro- 

 nized throughout a colony, in that the waves begin at the tip of each 

 hydranth simultaneously. Further, if one ties a ligature on any of the 

 uprights in a colony, the hydranth at the apex of that upright will, 

 in time, begin to beat out of synchrony with the rest of the colony. 

 In other words, disrupting the integrity of the colony (both tissue 

 and coelenteron fluid ) eliminates the synchrony. Even if one accepts 

 the conclusion that Cordylophora has nerve cells (Mackie, this 

 symposium), I find it difficult to envision how a stimulus is trans- 

 ferred through a colony in such a manner that each hydranth begins 

 a perstaltic wave at the same time. I would suggest, however, that 

 the synchrony indicates an order of integration in these colonial 

 organisms which we have not hitherto suspected. I suspect also that 

 understanding of colony development will involve further consider- 

 ation of the orientation, rhythmicity and synchronization of the 

 peristalisis. 



On superficial examination, a Cordylophora colony looks like 

 a forest of little trees. I have attempted to distinguish the component 

 events which produce this forest, and in so doing have found it pos- 

 sible to describe in simple, quantitative terms how the forest de- 

 velops. Careful observation of colonies reveals that they are entirely 

 composed of a series of interconnected pipes, each consisting of a 

 cylinder of tissue surrounded by a tubular perisarc." These tubes 

 are of essentially uniform diameter. Thus one can conceive of a 

 Cordylophora colony as a plumbing system with 0.2 mm. pipelines; 

 the description of a colony can be reduced to a description of the 

 kinds of tubes which comprise it, the relative positions of these 

 tubes with respect to one another, and the way in which they are 

 formed and grow. 



Stolon tubes, as they grow along the substratum, can give rise 



^This approach to tlie colonies excludes the hydranths from consideration. Interesting 

 observations on factors influencing the shape of hydranths, as well as entire colonies, 

 have been presented by Kinne ( 3 ) . 



