132 LECTURE vn. 



and discliarging the ova, wliich, as Steenstrup conjectures, in tlieir 

 turn develope the fixed polype-shaped Coryne. This stage of the 

 cycle has not yet been the subject of observation ; but, by the 

 analogy of the larger Meduste, is the more probable process than 

 that direct metamorphosis of the medusifoi-m individual into the pe- 

 dunculate polypoid individual, which V. Beneden has described by 

 the aid of a conjectural figure in the Tuhularia.* 



In the Eudendrium racemosum Sir J. G. Dalyell observed the germ- 

 vesicles containing the young medusoid animal to be developed from 

 many parts of the parent stem. A very active movement of the 

 inclosed animal may be seen near the mouth of the ovicapsule. It 

 then opens ; a small white bud protrudes, then some tentacula, in 

 active struggling motion ; and at last a little free-swimming medusoid 

 animal appears, in the shape of a small bell. It courts the light, and 

 manifests all the characteristics of the Acalephse. 



The medusiform ovigerous locomotive or distributive individual of 

 the Coryne Fritillaria, and Campannlaria dichotoma is obviously 

 homologous with the polype-shaped ovigerous individual which seems 

 to nurse, as it were, the ova into planulaj in the Campanularia 

 genicidata ; and the nutritive gemmiparous individuals in all the 

 compound Hydrozoa would seem rather to manifest the typical form 

 of the species, as the leaf is a more typical form of the plant than the 

 parts of the flower. Superadd, however, distinct nutritive and 

 circulating organs to the free-moving ovigerous individual, and 

 prolong its existence, and it would then cease to have the sub- 

 ordinate character of a nurse to the ova of the fixed individuals, and 

 would assume that of the perfected form of the species ; and such, in 

 fact, is the case with the larger gelatinous Radiaries called 'Medusai.' 



When the ovicapsule is the seat of development of a medusoid 

 oviparous individual, as observed by Dalyell, the phenomena attend- 

 ing the escape of these are ?emarkable. Great exertions are made to 

 force the orifice, until the animal finds its way out. The vessel of 

 sea water in which specimens of Eudendrium ramosum have been 

 kept is sometimes found crowded with the medusoid animalcules : 

 this phenomenon much surprised the venerable Scottish Naturalist 

 until he became aware of the origin of the little larvae. His observa- 

 tions have been confirmed by Sars and others on the Podocoryne 

 carnea and the Coryne nutans. In the same month in which Sars 

 observed the development of Medusoid animalcules from the Podo- 

 coryne carnea, he found other specimens of Podocoryne developing 

 clear capsules containing ova. Steenstrup, who was more successful 



♦ CXI. pi. 2. fig. 5. 



