AND THE LOWER ANIMALS. 233 



Leuckart, without seeking, like Owen and Steen- 

 strup, to discover the minute nature of the phenomena, 

 compared geneagenesis to metamorphosis.* Accord- 

 ing to his ideas, every scolex is a species of larva. The 

 Scyphistoma is, so to speak, a medusan caterpillar. 

 We do not think this view has any foundation, and 

 in this we fully coincide with Steenstrup, who, before- 

 hand, refuted most of Leuckart' s arguments. "The 

 nurse condition," said the Danish naturalist, " differs 

 entirely from that of larva. The caterpillar is itself 

 converted into a butterfly. The Scyphistoma never 

 becomes an Aurelia." 



The force of this reasoning is the more apparent, 

 as we often find the two phenomena, metamorphosis 

 and geneagenesis, in the same animal. For example, 

 in the Medusa, after the ovum has been transformed 

 into a ciliated larva, the latter is converted by meta- 

 morphosis into a Scyphistoma; then geneagenesis ap- 

 pears and produces the strobila, whose proglottis — 

 which is isolated, at first, under the form of Ephyra 

 — is afterwards metamorphosed into an Aurelia. In 

 this case the ciliated larva is really the larva of the 



already said, in these times, the expression proposed by the illus- 

 trious English zoologist would hold ground by being applied to 

 phenomena of an entirely different order, to which the serious atten- 

 tion of physiologists is being drawn. The result has proved the accu- 

 racy of these preconceptions, and farther on I shall have to treat of 

 true parthenogenesis, our earliest notions of which are due to Pro- 

 fessor Owen. 



* " Ueber Metamorphose ungeschlectliche Vermehrung Genera- 

 tionswechsel," 1851. — Zeitschrift fur Wissenschaftliche Zoologie. 

 My knowledge of this work is confined to Claparede's analysis in the 

 " Bibliotheque universelle de Geneve." But the interpreter's name 

 guarantees the accuracy of the interpretation. 



