436 PHYSIOLOGY. 



If we compare this structure of the parts of 'the skeleton with those 

 found in the vertebrata we discover a not unimportant uniformity in their 

 fundamental composition. That point namely from which the arch of 

 both rings -proceeds is analogous to the body of the vertebra ; the bow 

 of the smaller ring presents itself as the foramen medullare, and that of 

 the larger ring those moveable processes which hang attached to the 

 vertebrae, and which are called ribs ; the superior and generally smaller 

 half ring, lastly, which unites the two arches of the lower half ring to a 

 whole ring, represents the sternum placed between the ends of the 

 ribs. Hence, thus we obtain as the fundamental form of the skeleton 

 of the insect the vertebrae with their radiations, just the same as these 

 bones form the foundation of the trunk and head-bones of the vertebrata. 

 The difference between both is found only that in the vertebrata the 

 radiations of the vertebras take an opposite direction, whereas in insects 

 they project on one side only. Besides, this view, which appears to 

 contain so much truth as not to require a proof in detail, is by no 

 means new, but has been advanced by several comparative anatomists, 

 namely, Geoffroy St. Hilaire *, Robineau Desvoidy t, and more 

 recently by Carus ^. We need, therefore, merely refer to the labours 

 of these learned men, particularly to the last, and those who shall 

 consider this comparison an absurdity, we draw their attention to his 

 detailed representation ; it here suffices to have found the result in 

 a simple development. 



257- 



But that the vertebrae here lie upon the surface, whereas in the 

 Osteozoa they are encompassed by soft parts, is grounded upon the entire 

 formative type of the Arthrozoa, which is no other than that the 

 skeleton in them is always external, whereas in the Osteozoa it has 

 become internal. But why this is so ordained by nature we can only 

 answer when we shall have seen why nature has produced Gaslro-, 

 Arthro-, and Osteozoa, and to answer this would be stepping beyond 

 those limits within which human investigation is restricted, especially 

 in its inquiry into final causes ; consequently a miscalculation of its 

 capacity. But one thing strikes us with astonishment, namely, that in 



* Annales des Sciences Physic. Part iv. 1820, p. 96 133., whence translated iu 

 Meckel's deutschen Arclriv fur die Physiologic, torn. vi. p. 59. 



f Recherches sur 1'Organisation vertebrale des Crustaces, &c. Paris, 1828. 8vo. 



J Von den Urtheilen des Knochen und Schalengeriistes. Leipz. 1 830. Folio, with plates. 



