206 ANIMAL PHYSIOLOGY. [LESSON 59. 



sized dog, its saliva would be as immediately and certainly fatal as 

 the bite of a rattlesnake ? 



887. The pain that we share with domestic and other animals, 

 from the bite of parasitic insects, is solely due to this cause inocu- 

 lation by their saliva. 



888. The division of the salivary glands amongst the reptiles 

 would appear to throw some light on the function of each, or certainly 

 some of them ; thus : the poisonous reptiles possess only parotid 

 glands, the secretion of which descends by the channels of the fangs 



of the upper jaw (Fig. 331, a) ; the use they make of 

 them would seem to establish the function and proper- 

 ties of these particular glands. 



889. The Boa Constrictor (Python tigris) has no 

 parotid glands, neither can he destroy his prey by a 

 bite, but he entwines his body around his victim, and 

 kills him, as a bear would, by an embrace. But what 

 is now to be done ? he has no grinding teeth to enable 

 him to insalivate the food and loosen the tissues, by partially decom- 

 posing the body of the goat he has killed, and so prepare it for the 

 action of his stomach ; in other words, how can he perform the im- 

 portant function of insalivating it ? 



890. He does it in this way : Tie licks it all over, and wherever 

 the tongue, covered with saliva, touches it, the flesh becomes almost 

 rotten under its influence. 



891. Now, as it is well known that persons have been bitten by 

 a rabid dog and escaped hydrophobia, whilst other persons have been 

 bitten by sound and healthy dogs and yet this fearful disease has 

 supervened, how is this to be explained, unless we admit the differing 

 chemical property of the salivary glands respectively ? 



892. If the teachings of the rattlesnake and the boa constrictor 

 have any practical value, it would appear that the parotid glands 

 alone possess the power of destroying life, and that the secretion of 

 the other glands can only be employed upon already dead matter, to 

 effect its speedy decomposition. 



893. If this theory be true, it is very easy to explain the bites 

 and their consequences of the two dogs : in the case of the rabid dog 

 whose bite proved innocent, the saliva of inoculation may have 

 come only from the submaxillary and sublingual glands, and con- 

 sequently it was harmless ; whereas, in the case of the sound dog, 

 the saliva came from the parotid glands, and was therefore fatal. 



894. This view is sustained by the following considerations : the 



