80 ORGANS OP SENSE. 



amputating the tentacles the animal is no longer able to direct 

 its movements towards savory and odorous morsels as did the 

 Arion mentioned above. Dr. Sochaczewer of Berlin, however, 

 does not believe the olfactory organ in terrestrial mollusca to 

 reside in the tentacles. A Helix deprived of its tentacles never- 

 theless manifested perfectly its repulsion for the odor of turpen- 

 tine, _yet a small rod dipped in the essence was held between 

 the tentacles of another Helix without the animal manifesting 

 any sensibility of its vicinity. Dr. Leidy locates the*, sense of 

 smell in a "blind sac or depression opening below the mouth," 

 the mucus canal or Si^ius of Kleeburg. In the fresh-water pul- 

 monates, Lacaze-Duthiers locates the olfactory organ in a 

 depression of the external side of the basal enlargement of the 

 tentacles. 



The seat of the organ in the prosobranchiates and lamelli- 

 branchiates has not been determined. 



Kolliker has made the interesting discovery that a pair of pits 

 or papillae, as the case may be, situated behind or above the eye 

 in the Cephalopoda, are olfactory organs. The}'^ are pits above 

 the eyes in the Teuthidse and Sepiadse and in some of the octo- 

 j)ods, but in Argonauta and TremoctopuS they are developed as 

 papillae, and in Nautilus are elongated like small tentacles, placed 

 immediately behind the eyes. D'Orbigny has mistaken them for 

 external ears. 



Many of the mollusca give forth a perceptible odor, agreeable 

 or otherwise, such as the musky smell of the Eledone squid arid 

 of the snail Hyalina fragran». Another snail {Helix fastens) is 

 fetid, several give out an odor of garlic, Bulimus decollatus 

 resembling laudanum, and Clausilia and Pupa something like 

 sperm. 



Apropos to this subject is the following " Note on the Origin 

 of Ambergris," published by Mr. H. Crosse in Jour. Gonohyl. 

 (3 ser.,iii,'~204, 1863): 



All the world is acquainted with ambergris, so frequently used 

 as a perfume, either singly or in combination with other sub- 

 stances ; but the singular conditions under which it is produced 

 are by no means so well known. It is produced by the cetaceans 

 called cachelots, and is simply a result of digestion, a sort of 

 intestinal calculus, a coprolite. This has been confirmed by 

 numerous observers, including both scientific men and whalers. 

 It is formed into balls of various sizes in the digestive canal 

 and appears with the excrement. It is probably caused by an 

 unhealth}'- state of the animal, as the quantity differs in different 

 individuals from a few to a hundred kilogrammes, according to 

 whalers, and some animals have none. It is encountered in 

 many parts of the world, floating on the surface of the water, 

 than which it is much lighter. And now for the connection of 



