

ZOOGENY. 417 



rucic is to the abdominal cavity ; the olfactory membrane 

 to the tongue, as the lung is to the stomach. It is a 

 cephalo- thorax. The nose is not therefore so completely 

 closed as the mouth, but is opened through the two most 

 anterior air-holes or spiracula. The nasal apertures or 

 nostrils are the last persistent remnants of the spiracula, 

 after all those upon the sides of the body have been 

 closed up. 



:247.2. It is the last organ of sense, which has been 

 evolved from the trunk. It is therefore nobler than the 

 two others, and has also a nobler object, the air. 



2473. The nerves of the olfactory organ are peculiar 

 to it, and are encephalic nerves. As the sense of smell is 

 the pulmonic or arteriose sense ; so also does the arteriose 

 substance of the brain combine with this organ. The 

 olfactory nerves consist of cineritious or gray substance, 

 and are only prolongations thereof. 



2474. This is the only phenomenon of the kind met 

 with among all nerves, but it is commensurate with the 

 character or signification of this organ. A sensible pul- 

 monary organ can only have arteriose nerves. As the 

 liver is throughout venous, so is the nose throughout 

 arteriose in quality. 



b. ANIMAL SENSES. 



2475. It now only remains for us to consider the 

 motor and the sensitive system proper upon their highest 

 stage of development. The motor system, when repre- 

 sented in the nervous system, is* a peculiar organ of 

 sensation, as is likewise the nervous system itself upon 

 attaining its highest state of development. 



4. Osseo-Muscular Sense. 



2476. The lowest condition of the motor system is 

 the limbs, which represent no peculiar sense, but only 

 the sense of feeling refined or set in motion. This motor 

 system ascends into the head, and there no longer exercises 

 its motive powers in prehension, progression, &c., but 



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