CNIDARIA 



49 



in hydroineclusae. In the case of the latter the buds may be developed 

 on the manubrium (Sarsia siphonophora, Lizzia), at the base of the 

 tentacles (Sarsia prolifera, Codonium codonophorum), on the ring-canal, 

 or at other places. Concerning budding in the Cuninas consult p. 58. 

 A remarkable kind of reproduction by budding has been observed by 

 Brooks (No. 18) in a Eucopid, Epenthesis McCradyi. In this case 

 numerous blastostyles enclosed in a chitinous gonangium sprout out' 

 from the surface of the four gonads belonging to the radial canals; by 

 further budding small medusa are produced on the blastostyles. Ac- 

 cordingly, if the interpretation of these blastostyles as metamorphosed 

 hydranths should be definitely established, we should have in this case 

 an exception to the rule that by the budding of a medusa there can 

 never be produced anything but a medusa. 



From the form of non-sexual reproduction— lateral budding— thus far 

 treated of, must be distinguished the reproduction of a hydranth from the 

 free end of the stalk, such as has been observed after injuries, after the 

 spontaneous detachment of the hydranths, as in Tubularia (Dalyell, 

 No. 4 ; Allman, No. 15), and after the death of the polyps in consequence 

 of their being overgrown by algaj, as in the case of Campanularians 

 (v. Lendenfeld, No. 38). 



In addition, reproduction by division has been observed in Hydroids 

 in certain cases, thus by Metschnikoff (No. 12) in the blastula-stage 

 of Oceania armata, by Ussow (No. 48) in the buds and in the mature 

 animals of Polypodium hydriforme, which is parasitic in its early stages 

 in the eggs of the sturgeon, and also as the only method of reproduction 

 hitherto observed in the North American fresh-water Microhydra Ryderi 

 and in Protohydra (Geeeff). Furthermore the occurrence of spontaneous 

 division in Hydra has been maintained by the earlier observers. 



Reproduction by means of division has also been observed in the young 

 of certain medusae ; it is introduced by the budding of a new stomach ; 

 this is followed by a grouping of the radial vessels around the two 

 existing manubria as centres and a fission of the disc, which begins at 

 the margin. Such is the case with Stromobrachium mirabile (Kolliker, 

 No. 37), Phialidium variabile (Davidoff, No. 23), and Gastroblasta 

 Raffaeli (Lang, No. 39). The newly formed radial canals grow out from 

 the marginal canal as centripetal vessels. Owing to the fact that in later 

 stages the budding of the gastral sacs continues and the division of the 

 individuals does not keep pace with it, in fact ceases altogether, colonies 

 are produced (Gastroblasta Raffaeli and timida — Keller). 



Another method of non-sexual reproduction, which has been called 

 frustulation (Allman, No. 15), may best be defined as an early 

 abstriction of an only slightly developed lateral bud. In the case of 

 Schizocladium ramosum, a Campanularian, there are on the polyp 

 colony lateral branches which bear no hydranths. From the ends of 

 these are constricted off small portions, which, except for the absence of 

 cilia, resemble a planula ; for they attach themselves, become surrounded 

 K. H. E. E 



