OF THE INVERTEBRATE ANIMALS. 27 



and we thus arrive at the interesting result, that ^Ae substance of the 

 tegument of an articulate animal contains the elements of its primi- 

 tive muscular bundle, plus one of the so-called hydrates of carbon, 

 i. e. sugar, gum, woody-fibre, &c., and thus that we can very well 

 explain the formation of this substance in such enormous quantity 

 and so comparatively short a time by the coalition of muscle, i. e. 

 blood or proteine, and woody-fibre, into this peculiar combina- 

 tion. Would not the Craw-fish, if its tegument were reproduced 

 merely from the albuminates of its organism, perish from loss of 

 substance on changing its shell? Do we not see here a wise 

 oeconomy of nature, in causing a large part of the cytoblastema to 

 be formed of calcareous salts, two- thirds of the remainder by 

 hydrates of carbon (Algae, Confervae, &c,) which are at hand, and 

 the latter third only by the fluid mass of the animal ? We do 

 not find the stomach and intestinal canal of these animals, at or 

 soon after the period of the casting of the tegument, filled with 

 stems of Charae, pieces of Conferva, &c. without a reason ! Those 

 which consume vegetable substances (as the Cockchafers, so many 

 thousands of which we frequently find living on the leaves of one 

 tree, that we cannot resist the idea of the principal constituents 

 of the vegetable cell, gum and woody-fibre being assimilated by 

 them) therefore produce their cutaneous system from woody- 

 fibre and vegetable albumen ; whilst on the other hand, those 

 which feed upon animal matters mostly devour the weaker 

 members of their families, and from them obtain the requisite 

 chitine, already prepared and formed. May we not have here 

 the same relation as in the higher Vertebrata? Does not the 

 total effect appear here also to be diminished by the withdrawal 

 of a certain amount of power for the production of the formative 

 material, so that as regards the faculty of perception and volition 

 we are obHged to yield to the Carnivora a position above the 

 Phyllophaga ? 



Of course these views will remain hypothetical, although highly 

 probable, until they have been proved to be correct by direct 

 observation. Now this proof may be obtained with sufficient 

 accuracy in two ways : — 



1. By tracing the history of development in a chemical point 



of view, for instance, of the Lobster. This method would not be 



very difficult; for according to Rathke's observations on the 



Craw-fish*, its cutaneous skeleton is not formed until the latter 



* I,oc. cil. pp. 11, 55, 63. 



