SMELL — GENERAL 9I 



combine the ability to receive chemical particles with the 

 delicate sense of touch. 



In the reptiles — particularly snakes and lizards — the 

 tongue acts as a detector of smells in conjunction with the 

 organ known as Jacobson's organ. This is situated in the 

 roof of the mouth in the form of sensitized pits to which scent 

 particles are conveyed by the tongue and then translated 

 into messages of scent in the brain. (See Plate 7.) 



In the amphibians the sense of smell is present and is 

 closely related to taste. Investigations into the scenting 

 powers of amphibians — notably those of Dr. Maxwell Savage 

 — tend to show the possibility that frogs and toads find their 

 way to their spawning places by means of the smell coming 

 from the waters used for breeding, and which is caused by 

 the particular scent of minute plants in the ponds. The 

 scent is diffused into the air and so to the amphibians them- 

 selves and, aided by the air currents close to the ground, 

 can enable the frogs and toads to select by scent those ponds 

 which contain the right plants for the support of the tadpoles 

 which will hatch from the eggs in due course. In addition, 

 the actual chemical content of the water will play some part, 

 as this will, to a considerable degree, affect the plant growth 

 in it. 



Many other aquatic animals, including fish, have powers 

 of scent which, in the main, are used for the detection of 

 certain kinds of food. This applies to marine animals as well 

 as fresh-water species. 



Fish have a highly developed sense of smell, and in a 

 great number of species this is the way in which they locate 

 their food. Of course, predatory fish, such as pike and perch, 

 hunt by sight, but not all carnivorous fish rely on their eyes. 

 Sharks, for instance, can smell blood or flesh from great 

 distances and may well be the best scenters among the 

 fishes. 



Many fishes take water, with its dissolved chemical scent 

 particles, into their nasal cavities where it comes in contact 

 with specialized cells capable of appreciating the scents so 

 conveyed. 



Anglers will be familiar with other kinds of fishes which 

 have on their lower jaws fleshy finger-like processes known 



