102 SURVEY OF THE REPRODUCTIVE PROCESS 



§ 10. ARTICULATA. 



Among the higher Articulata, it is only in a few aberrant 

 species that we have any obvious manifestation of gemma- 

 tion ; consequently, though in these exceptional cases, we 

 meet wth some well marked examples of " alternation," 

 such phenomena are not in accordance ^\dth the general 

 course of development in this type of organization. 



It may be necessary in some degree to qualify this state- 

 ment, as applicable to the Myriapoda, for as these approach 

 the Annelida in configuration, so they do also in multiply- 

 ing their segments up to a certain point, by a process of 

 gemmation from the penultimate segments, subsequent to 

 the emission of the embryo from the egg, though no in- 

 stances are known of spontaneous fission of the body.* 



A striking feature in the reproductive process among 

 Articulata is what is called metamorphosis. In Insects par- 

 ticularly, and also in many Crustacea, the embryonic form 

 first assumed often differs very widely from that of the 

 adult, in the conformation of its parts both external and in- 

 ternal, and this not merely in its organization being rudi- 

 mentary, but in a total dissimilarity of particular organs or 

 members, and even in the existence of structures which 

 afterwards waste or entirely disappear by absorption, or are 

 throAVTi off from the body. Metamorphosis, indeed, is not 

 confined to this division of the Animal Kingdom ; allusion 

 has before been made to its occurrence in some of the other 

 groups, and, as a general rule, it may be said to be more 

 marked in proportion as the typical organization becomes 

 more elaborate. It is nowhere, however, more observable 



* According to Fabre, tlie larva of Scutigera lias at first only the seven 

 anterior segments, containing the organs of sense and the digestive ap- 

 paratus ; the posterior segments — those behind the large plates or elytra 

 — are of later formation. It is in this region, as in the case of the Anne- 

 lida, that the reproductive organs are situated. Annals of Nat. Hist., 2d 

 Ser., XIX., 165. 



