130 THE NATURE AND VARIETIES OF 



In the Protomorphic alternation, therefore, of the Tre- 

 matoda, we speak of the typical organism and its germ-like 

 matrix ; in the Gamomorphic alternation of the Polypifera, 

 of the typical organism and its sexual offset. Both the 

 matrix and the offset may assume, indeed, the form of in- 

 dependent beings, but their life is always transitory and 

 provisional, having reference to one common end the 

 multiplication of the race though by different means. 



development of Medussa from the egg without passing through the polype 

 stage. It is said to occur in Pelagia noctiluea (Krohn), (Eginopsis Me- 

 diterranea (Miiller), and Trachynema ciliatum (Gegenbaur). Annals 

 of Nat. Hist., 2d Ser., IX., 37, XVII., 285. Huxley in Medical Times, 

 XII., 506. 



Professor Huxley, in retaining the term Medusidae for such cases, re- 

 marks " It is not yet proved that any of them are developed directly 

 from the eggs of similar organisms. I by no means wish to question the 

 great probability of the supposition that those ciliated embryos which 

 were observed by Miiller and Gegenbaur to pass directly into the Medusae, 

 proceeded from the eggs of similar Medusae. But, I repeat, there is no 

 proof of the fact." Oceanic Hydrozoa, p. 21, and note. I am equally 

 unable to harmonize some of the statements of Mr. Lewis. He cites Pro- 

 fessor Kolliker as having " seen the same species of Campanularia pro- 

 ducing both eggs and Medusae," and goes on to mention that he himself 

 had " on the same polypidom found some of the capsules filled with eggs, 

 and some with Medusae," and that in different specimens of one species 

 (Plumularia NyriopTiyllum) " dredged at the same time, and from the 

 same place, he found capsules containing eggs and also Medusce ; 

 and others but not on the same polypidom containing eggs and 

 polypes, i.e., the ciliated gemmules which we know to be the infusorial 

 stage of the polype." These observations though unfortunately not 

 stated with the fulness and precision necessary on such a point seem to 

 point either to the conclusion, that the same species may bear sporosacs 

 with true ova, and free medusoids, the latter developed from gemmae 

 closely resembling ova or to another result, still more at variance with 

 our received views viz., that true ova, formed within the capsules 

 (sporosacs ?) of the polype, and actually impregnated, may undergo di- 

 rect development into Medusae. Sea-side Studies, p. 296. 



Van Beneden, it may be observed, is quoted by Carpenter for the ob- 

 servation that in some Tubularida both attached ovarian cysts and free 

 medusoids are developed, with no difference that can be traced in their 

 respective products. Compar. Physiol., 539. 



