K. G. CARUS 99 



The thesis which Carus sustains is that all forms of 

 skeleton, whether of dermatoskeleton, splanchnoskeleton, or 

 neuroskeleton, can be deduced from the hollow sphere, which 

 is the primary form of any skeleton whatsoever (p. 95). 

 That means, put empirically, that every skeleton can be 

 represented schematically by a number of hollow spheres, 

 suitably modified in shape, and suitably arranged. The 

 chief modification in shape exhibited by bones is one which 

 is intermediate between the organic and the crystalline series 

 of modifications of the sphere. The organic modifications 

 are bounded by curved lines, the crystalline by straight ; the 

 intermediate partly by curved and partly by straight lines. 

 They are the dicone (the shape of a diabolo) and the 

 cylinder. These forms must necessarily be of importance 

 for the skeleton, which is intermediate between the organic 

 and the inorganic. " The dicone embodies the real 

 significance of the bone," writes Carus. Each dicone and 

 cylinder composing the skeleton is called by Carus a 

 vertebra. 



We may expect then all skeletons to be composed of 

 spheres, cylinders and dicones in diverse arrangements. 

 Nature being infinite, all the possible types of arrangement 

 of these elements must exist in the test or skeleton of some 

 animal, living, fossil, or to come (p. 127). One conceives 

 easily what the main types of skeleton must be. In some 

 animals, e.g. t sea-urchins, the skeleton is a simple sphere ; in 

 others, e.g., starfish, secondary rows of spheres radiate out 

 from a central sphere or ring ; in annulate animals the 

 skeleton consists of a row of partially fused spheres. 



In Vertebrates the arrangement is more complex. There 

 are first the protovertebral rings of the dermatoskeleton, these 

 being principally the ribs, limb-girdles, and jaws. Round 

 the central nervous system are developed the deutovertebral 

 rings of the neuroskeleton (vertebrae in the ordinary sense). 

 The apophyses and bodies of the vertebrae, and the bones 

 of the members 1 are composed of columns of tritovertebrae, 

 or vertebrae of the third order. Thus the whole vertebrate 

 skeleton is a particular arrangement of vertebrae, which 



1 Dutrochet in 1821 had tried to prove that the bones of the 

 members belong to the type of the vertebra the dicone. 



