46 



T. KOMAI : STUDIES ON TWO ABERRANT CTENOPHORES 



'I'cxt-fijTure 2. Coeloplana 

 bocki KoMAl. An indivi- 

 dual laying eggs, jicen from 

 the ventral side. x8. 



may be laid practically at any time of the 

 day. I found them laid somitimes in the early 

 morning, at other times in the daytime and at 

 still other time at mid-night. The eggs do not 

 become pelagic as in the ordinary ctenophores; 

 they are kept under the body of the mother 

 animal, where they undergo development and 

 reach the stage in which the larva is complete- 

 ly formed. The number of eggs carried by an 

 individual is generally from ten to fifty, but 

 may be as large as two hundred. They are 

 all agglutinated together by gelatinous strings 

 of an extremely sticky nature. All eggs in the 

 same cluster are in nearly the same stage of 

 development. 



Unsegmented eggs (PI. 6, fig. l) show 

 essentially the same structure as those of pelagic 

 forms. A distinct membrane {c. m) envelops 

 each Qgg- The space between the membrane 

 and the egg-body is relatively narrower than in eggs of those forms, 

 so that the egg-body may almost be said to be in direct contact with 

 the membrane, which fact being far from the case with the eggs of the 

 pelagic forms. The space appears to be filled with a thin gelatinotis 

 substance. The non-pelagic characteristic of the eggs is apparently due 

 to the scantiness of the gelatinous substance in that space. 



The size of the egg varies slightly. The entire egg surrounded 

 by the membrane measures in an average diameter about 0.3 mm. and 

 the egg-proper 0.25 mm. As in ordinary ctenophores, the egg-body 

 consists of the superficial membrane (fig. 3, jr. in), the ectoplasm (fig. i, 

 3; ec. pi) and the endoplasm {eii. fil). The superficial membrane is 

 extremely thin and devoid of granulations. The ectoplasm is much 

 thicker and occupies the peripheral parts of the egg-bod>'. It has the 

 same thickness all aiound the egg, and presents a granular appearance. 

 The endoplasm occupies by far the greater part of the egg-body and 

 shows a coase alveolar structure. The alveoles are rather small as 

 compared with those of the eggs of pelagic forms. Two polar bodies {p) 

 are frequently .seen lying on the surface of the egg-body. They are 

 either spherical or more or less Battened. More rarely, there occur three 

 bodies lying side by side, apparently restilting from the division of the 



