HISTORY OF PARTHENOGENESIS. 287 



not two species, but two generations of tlie same species. 

 The solitary Salpa produces the chain-salpa by " budding ;" 

 and the chain-salpa by "alternation of generations" (the 

 phrase is Chamisso's) produces the solitary salpa by ova. 

 Krohn, Huxley, Leuckart, and Vogt (alas ! only one English- 

 man among four Germans), have since confirmed Chamisso's 

 discovery, which, as Mr Huxley has pointed out, gives him 

 the priority over Steenstrup, not only as to the mere phrase 

 of " alternate generations,'' but as to the distinct conception 

 of the idea implied in the phrase. Nine years afterwards, in 

 1828, Milne Edwards first announced a similar mode of repro- 

 duction among the Ascidians (such as I sketched it just now), 

 without, however, connecting it with Chamisso's discovery. 

 In 1835, the Norwegian pastor and indefatigable naturalist, 

 Sars, opened that wonderful series of revelations which by 

 himself, Loven, Lister, DalyeU, Steenstrup, Van Beneden, 

 AUman, Forbes, and others, have established the alternation 

 of generations in Polypes and Medusas. 



A not less surprising alternation has been discovered in 

 the Entozoa ; but it would occupy too much space to narrate 

 here, requiring much preliminary explanation before it could 

 be intellisible to the general reader. * Let us continue our 

 history. 



In 1842, the known facts were collected, and connected 

 under one generalisation by the Danish botanist Steenstrup, 



» The student will find a complete liistory of these phenomena in Siebold, 

 Ueber die Band-und-Blaseawurmer, 1S54, or in the lai-ger work of KiiCHEN- 

 MKiSTER, Die in und an dem Korper des lebenden Menschen vorkomenenden 

 Parasiien, 1855 ; a translation of which, by Dr Lankester, has been published 

 recently by the Sydenham Society. 



