CONSIDERATIONS. 135 



continue during the whole of the animal's life, or does it cease 

 as soon as it becomes adult? Perhaps the latter is the connect 

 opinion ; for the Rev. Lansdown Guilding has observed, that 

 the larva of Phasma cornutum can reproduce the feet it may 

 have lost, though the imago cannot. 



In Nais, and some other Annelida, the body, if divided, 

 becomes two perfect individuals. 



Most of the Crustacea carry their eggs attached to the 

 body, not to assist in hatching them, but to protect them. 

 Some, however, abandon them as soon as they are laid. 



The Araneidce in general envelop their eggs in a silken 

 cocoon, where they remain until the young appear. The 

 Epeirce merely attach them to some solid body, and then leave 

 them ; others, Theridion, Pholcus, &c. (araigntes Jilandieres), 

 watch over the cocoon in some sheltered place, where they 

 have fixed it, to aid the escape of their young; others, the 

 Lycosce, carry the cocoon with them, to give to their offspring 

 the same maternal care. 



Insects, with the exception of the genus Termes, and most 

 of the Hymenoptera, simply deposit their eggs, and leave 

 them, without giving themselves any further trouble ; but 

 the care bestowed by the Insects forming the exceptions to 

 this rule is very remarkable. 



The eggs of some Orthoptera, as Mantis and Blatta, are 

 excluded, enveloped in a case, where each has its separate 

 compartment. 



The most singular fact in the generation of Insects is, that 

 no species, when hatched, has exactly the same form as the 

 parent, and only acquires it by two transformations, called its 

 metamorphoses. 



Among the Myriapoda, the Juli alone undergo meta- 

 morphosis. 



The Scolopendrce, the Thysanoura, the Pulmonary Arach- 

 nida and Phalangium, appear not to undergo any change ; but 

 the Acari and some of the Crustacea do. 



Part V. — Respiratory System. 



No where do we find the respiratory system carried to so 

 high a degree of development as in Insects; yet its functions 



