REPRODUCTION BY GEMMULES. 433 



they are sometimes observed completely at rest. If a 

 portion of one of the arms be cut off, the ciliary action 

 continues as vigorous as before, and the isolated part 

 is carried about in the field of the microscope as 

 though it were itself a living creature. 



The addition of a small quantity of carmine to the 

 water, wherein a few of the polyps are vigorously at 

 work, at once reveals the existence of powerful cur- 

 rents rushing along the tentacula towards the mouth, 

 which occupies the same position as in Bovierbankia 

 and other Polyzoa. The stomach is not furnished 

 with a gizzard in this species. The intestine forms a 

 considerable elbow at its origin, and is short and 

 wide, terminating, not, as is generally the case, near 

 the tentacular ring, but about midway up the body, 

 at a point opposite the base of the setae. 



During the spring season the aquariist will often be 

 able to detect minute whitish points, which are some- 

 times exceedingly numerous, disseminated through 

 the whole transparent substance of the gelatinous 

 polyparium. If one of these points be carefully turned 

 out with a needle, it is found to consist of a trans- 

 parent sac, wherein are contained, generally, from four 

 to six ciliated gemmules, which, as soon as the sac is 

 torn, escape and swim about with the greatest activity, 

 affording most interesting objects for microscopic ob- 

 servation (PL VII. fig. 9). 



It would be impossible to explain the variety of 

 motions which these gemmules are capable of exe- 

 cuting, were it not obvious how complete is their con- 

 trol over the action of the cilia, which are their sole 

 locomotive organs. Sometimes they simply rotate 



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