RESPIRATION. 81 



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this substance with our subject. The Cetaceans consume large 

 quantities of cephalopods as food, and raan}^ of these latter when 

 living exhale a strong odor of musk ; among these may be espe- 

 cialh' mentioned Eledone moschatus, and the gigantic Loligo 

 Boayeri. Now amidst the ambergris are found portions of the 

 corneous mandibles of cephalopods, which the digestion of the 

 whale has not been able to destroy. The ambergris is then, 

 without the least doubt, the result of the intemperate eating of 

 cephalopods. Some of our readers who appreciate the delicate 

 perfume of ambergris, will scarcel}' thank us for revealing to 

 them in what a singular laboratoiy it is reall}^ prepared ; but we 

 cannot change the realit}^ of things — and such persons can, if it 

 seem good to them, employ for the future perfumes of less pro- 

 saic origin. 



Gustatoiy Organic. The tongue and mucous lining of the 

 pharynx of cephalopods have been considered to possess gus- 

 tatory functions, having a crowd of smooth papillae which 

 probably serve this purpose. That this sense is possessed by 

 the Gastropoda is evidenced by the cai^e and discrimination with 

 which their food is selected, but its special seat has not been 

 determined, for the marine species. Fischer has discovered, in 

 the helices, two small nerves, coming from special ganglia or 

 distinct swellings of the cerebral ganglia, and which penetrate 

 the pharynx; these he thinks are gustator3^ The agnatha 

 (Testacel'la, Glandina), which feed on living prey, do not appear 

 to possess these special ganglia. 



The labial tentacles of the bivalves are considered to be organs 

 for discriminating food, but in what way is unknown. They 

 appear, however, to exercise little selection, and swallow anj^thing 

 that is small enough to enter their mouths, including living 

 animalcules, and even the sharp spicula of sponges. In some 

 instances, however, the oral orifice is well guarded. 



RESPIRATION. 



The respiratory process consists in the exposure of the blood 

 to the influence of air, or water containing air ; during which 

 oxygen is absorbed and carbonic acid liberated. It is a process 

 essential to animal life, and is never entirely suspended, even 

 during hibernation. Those air-breathers that inhabit water are 

 obliged to visit the surface frequently ; and stale water is so 

 inimical to the water-breathers, that they soon attempt to escape 

 from the confinement of a glass or basin, unless the water is 

 frequently renewed. In general, fresh water is immediatel}'" fatal 

 to marine species, and salt water to those which properly inhabit 

 fresh ; but there are some which affect brackish water, and many 

 which endure it to a limited extent. The depth at which shell- 

 fish live is probably influenced by the quantity of oxygen which 



