224 



SECOND SUBSECTION. 

 THE ANIMAL ORGANS. 



155. 



THE animal organs forming the systems of sensation and of motion no 

 longer displaya vegetable, but strictly a peculiar, purely animal character. 

 We have before seen ( 91.) that the intestinal canal, the vessels, and 

 the sexual organs are mere repetitions of vegetable structure, in as far 

 as they consist, like plants, of cells, tubes, arid thin membranes. But 

 we will now show that these aboriginal forms of structure are not 

 found in the animal organs. 



156. 



The characteristic of the animal organs is rigidity and solidity. The 

 entire organ is throughout of one structure, and consists of one sub- 

 stance, which, indeed, still frequently is encircled and enveloped by 

 vegetable forms, as for example, the nerves by thin membranes, but 

 these constitute no essential component of the peculiar mass, but serve 

 only as its exterior case or covering. 



If we examine the muscular system with this view we detect 

 solid fibres, which lie closely contiguous to each other, forming by 

 degrees larger bundles, that unite into an entire muscle. Even the 

 nicest microscopal investigation detects no cavity in the individual 

 fibres, but a solid uniform mass throughout. Each solitary fibre there- 

 fore is entire in itself, which, indeed, upon close examination, appears 

 divided by transverse partitions, and thus seems composed of cells, 

 but in fact it is not so. But we therein see the difference between the 

 vegetable and animal organs, the former growing into an individual 

 organ from the aggregation of consecutive vesicles or cells, and the 

 latter from the union of solid globules. The animal organs, therefore, 

 originate in the following manner; it is not cells added to cells, but 

 globules, animal atoms, as some naturalists express themselves, to 

 globules; a row of such globules form a solid fibre, several fibres the 

 bundle, and several of these a muscle or nervous cord. 



