ZOOGENY. 351 



pendent air-tube, or such as is commensurate with 

 animal nature. 



1969. In the artery the external integument has been 

 repeated in the nutritive system, and hence the gal- 

 vanism has become of a continuous character. 



1970. The artery must therefore be the highest 

 vessel, the most total of all terrestrial processes. For 

 it is the air-duct united with the intestinal vessel. It 

 contains mucus, which carries the properties of both 

 poles of the body in itself; there is oxydized mucus. 



1971. The artery contains the whole body, lung and 

 intestine, in short, the whole animal, (whereas it was pre- 

 viously dispersed in two vessels,) in a fluid state within 

 itself. From the artery therefore nutrition will directly 

 take place ; from it the animal will be formed. 



1972. The air or respiratory vessels may be viewed 

 as arteries carried to the very extreme. In the lung the 

 arterial system has attained its highest purity, the oxygen 

 only, without the indifferent substance, being contained 

 therein. The trachea is the roughest artery Arteria 

 aspera. 



1973. The arterial system, in accordance with its sig- 

 nification, makes its first appearance in water, because 

 the aquatic mode of respiration is less energetic, and 

 thus the mucus is more feebly decomposed. The Mol- 

 lusca, snails, arid many worms have a perfect arterial 

 system. The branchiae do not, like respiratory tubes, 

 pass into the body, as in insects ; but there are vessels 

 which take up the oxygen and convey it into the body. 



1974. As lung and absorbent belong to the pure air 

 or the pure water, so do artery and vein to the water 

 combined with the air. The two former are therefore 

 present only where aerial respiration occurs, and the 

 two latter where water merely is respired. 



1975. The last system is only present in animals, in 

 so far as they are aquatic in their habits. 



1976. Insects, as being purely aerial animals, have 

 therefore arteries and veins only so long as they are in 

 the larva or worm-like condition, and as flies or perfect 



