AND THE LOWER ANIMALS. 169 



of a small coleopteron* (Rhynchites betuleti), whichdoes 

 considerable damage to the vine plant, by gnawing 

 the buds, and rolling up the leaves, in order to 

 deposit its eggs in them. From the egg of 

 Ophionurus there is developed an infusoria-like 

 animal, which is transparent, has an almost homo- 

 geneous structure, presents posteriorly a few bristly 

 segments, and is possessed of a long tail, which it 

 whisks about with rapidity. In the interior of this 

 false larva there is slowly developed a sort of double- 

 jawed worm, which eventually entirely occupies the 

 place of the first animal, and then bursts from the 

 species of case formed by the skin of its parent, and 

 changes into a nymph, which will soon become a 

 perfect insect. This is an instance of the simplest 

 kind. The proglottis is directly produced by the 

 scolex, but it reaches the perfect condition only 

 through a metamorphosis. 



Associating this fact with what occurs among butter- 

 flies, we may say : From the egg there sprung a naked 

 caterpillar, which produced a hairy one, by a process 

 of internal budding, and this was then transformed 

 into a chrysalis and afterwards into a butterfly. 



Of the four classes included in the articulate division 

 of the Annulose sub-kingdom, only two — insects and 

 Crustacea — are reproduced by geneagenesis ; and even 

 among the latter the only example known is that of 



* The Coleoptera, commonly called beetles, have a single pair 

 of membranous wings, which are covered when at rest by the 

 horny elytra. 



[Philippi has since altered his opinions, and now regards the 

 peculiar development of Pteromalus as an instance of hypermeta- 

 morphosis rather than of development by nurses, as S teens trap 

 believed.— Tr.] 



