Chap. III. ANATOMICAL SYSTEMS. 201 



The system of Zoolog}-, publisher! by Ehrenberg in 18-36, presents many new 

 views in almost all its peculiarities. The most striking of its features is the prin- 

 ciple laid down, that the type of development of animals is one and the .'^ame 

 from Man to the Monad, implying a complete negation of the principle advocated 

 by Cuvier, that the four primary divisions of the animal kingdom are characterized 

 by different plans of structure. It is very natural that Ehrenberg, after having 

 illustrated so fully and so beautifully as he did, the natural history of so many 

 organized beings, which up to the publication of his investigations were generally 

 considered as entirely homogeneous, after having shown how highly organized and 

 complicated the internal structure of many of them is, after having proved the 

 fallacy of the prevailing opinions respecting their origin, should have been led to 

 the conviction that there is, after all, no essential difference between these animals, 

 which were then regarded as the lowest, and those which were placed at the 

 head of the animal creation. The investigator, who had just revealed to the 

 astonished scientific world the complicated systems of organs which can be traced 

 in the body of microscopically small Rotifera, must have been led irresistibly to the 

 conclusion that all animals are equally perfect, and have assumed, as a natural con- 

 sequence of the evidence he had obtained, that they stand on the same level with one 

 another, as far as the complication of their structure is concerned. Yet the diagram 

 of his own system shows, that he himself could not resist the internal evidence of 

 their imequal structural endowment. Like all other naturalists, he places Mankind 

 at one end of the animal kingdom, and such types as have always been considered 

 as low, at the other end. 



Man constitutes, in his opinion, an independent cycle, that of nations, in contra- 

 distinction to the cycle of animals, which he divides into Myeloneura, those with ner- 

 vous marrow (the Vertebrata,) and Ganglioneura, those with ganglia (th(> Invertebrata.) 

 The Vertebrata he suljdivides into Nidrieidia, those which take care of their young, 

 and Orphamzoa, those which take no care of their young, though this is not strictly- 

 true, as there are many Fishes and Reptiles which provide as carefull}' for their 

 young as some of the Birds and Mannnalia, though they do it in another way. 

 The Invertebrata are subdivided into Hphmimozaa, those which have a heart or 

 pulsating vessels, and Asph'/cfa, those in which the vessels do not pulsate. These 

 two sections are further subdivided: the first, into Articulata with real articulations 

 and rows of ganglia, and Mollusks without articidjition and with dispersed ganglia ; 

 the second, into Tubulata with a simple intestine, and Racemifera with a branching 

 intestine. These characters, which Ehrenberg assigns to his leading divisions, imply 

 neces.sarily the admission of a gradation among animals. lie thus negatives, in 

 the form in Avhich he expresses the results of his investigations, the very principle 

 he intends to illustrate by his diagram. The peculiar view of Ehrenbei-g, that 



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