316 SEA-SIDE STUDIES. 



Huxley, an account of which lie read to the Linnaean 

 Society, Nov. 5, 1857. That paper not being yet 

 printed, I can only refer to its conclusions in as far 

 as they bear on the present topic, and these are — First, 

 that the virgin viviparous Aphis, which is said to 

 produce broods of young by " internal gemmation," 

 does really produce them from, unfertilised ova : 

 every stage of the development of these ova, and that 

 of the embryos having been carefully made out. Se- 

 condly, that the female oviparous Aphis produces her 

 young from ova fertilised by spermatozoa ; but the 

 early stages in the development of these ova are pre- 

 cisely sirnilar to those of the viviparous Aphis, the 

 differences presenting themselves at a later period, 

 when in the one case the formation of the " mulberry 

 mass " takes place spontaneously, in the other case it 

 is preceded by the union of the spermatozoa with the 

 ova. As the product of both processes is identical — 

 as the Aphis which is seen to issue from an unfertilised 

 ovum is in all respects similar to that which issues 

 from a fertilised ovum — the conclusion is irresistible, 

 that Generation is possible from germ-cells only ; and 

 the facts I have brought forward respecting the Polypes 

 are thus seen to stand in no absolute isolation. 



Kesumino; in one schema the results of mv investi- 

 gations into Polypes, with those of my predecessors, 

 we find, — 



A. The Medusa parent jDroduces ova ; 



B. These ova are developed through an infusorial 

 stage into Polypes ; 



