F. S. CONANT ON THE CUBOMEDUS^. 21 



occasionally in males as well as females, and that in the females a series 

 can be traced with a good degree of certainty between the small floating 

 cells like those found in the walls, and the larger ones which have all the 

 characteristics of young ova. 



However that may be, this amoeboid action of cells having the struc- 

 ture of ova brings to mind the remarkable form of asexual reproduction 

 described by Metschnikoff for Cunina proboscidea, under the name of 

 " Sporogonie." Unfortunately Metschnikoffs original paper was not 

 accessible to me, so that I was unable to obtain more particulars on the 

 subject than those given in Korschelt and Heider's text-book (p. 33). 

 The reproductive organs of both males and females of Cunina proboscidea 

 are said to produce, besides the usual distinctively sexual elements, 

 neutral amoeboid germ cells, which wander into the endoderm of the 

 stomach and circular canal, and also penetrate into the gelatine of the 

 subumbrella. These amoeboid cells divide parthenogenetically. One of 

 the two cells of the first cleavage continues to divide and eventually 

 forms an embryo of Cunina ; the other remains amoeboid and serves for 

 movement, attachment and nourishment of the embryo. 



Charybdea, however, has shown no sign of any such reproductive 

 process on the part of its floating and wandering cells. The only indica- 

 tion that I get as to their use points to a possible nutritive function. 

 The enlarged terminal portion of the canal of the sensory club almost 

 invariably contains a number of the small-sized floating cells. These 

 have a vacuolated, half disintegrated appearance, with the nucleus always 

 compact and brightly staining. Now, examination of the high columnar 

 cells that line the enlargement of the canal shows the presence in the 

 cells of bodies of exactly the same appearance as those in the lumen. In 

 one case a floating cell was found just at the end of an epithelial cell, to 

 all appearance half ingested. The identity of the bodies inside the cells 

 and those in the lumen is shown very clearly in some sections of material 

 fixed in formalin, which preserves nuclei, cell walls and general outlines 

 well enough, but does not retain the cytoplasm, and hence is useless for 

 most purposes of histology. In the endodermal cells of the terminal 

 enlargement thus preserved are found all the more distinctly the bright, 

 compact, degenerated nuclei of the ingested cells, while in the lumen are 

 seen other bright, compact nuclei with the poorly preserved remains of 

 cell substances around them. In addition to the evidence from the 

 appearance of the floating cells themselves and their ingestion by the 

 endodermal cells, a little collateral evidence may perhaps be brought in 



