358 ANNUAL OF SCIENTIFIC DISCOVERT. 



has no grinding teeth to enable him to insalivate the food and loosen the tis- 

 sues, by partially decomposing the body of the goat he has killed, and so 

 prepare it for the action of the stomach; in other words, how can he per- 

 form the important function of insalivating it? 



He does it in this way : he licks it all over, and wherever the tongue, cov- 

 ered with saliva, touches it, the flesh becomes almost rotten under its influ- 

 ence. Now, as it is well known that persons have been bitten by a rabid 

 dog and escaped hydrophobia, while 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? 



If the teachings of the rattlesnake and the boa constrictor have any prac- 

 tical 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 em- 

 ployed upon already dead matter, to effect its speedy decomposition. 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 consequently it was harmless ; whereas, in the case of the sound 

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

 view is sustained by the following considerations : The ducts of the parotid 

 glands are situated, as we haA r e seen, in immediate proximity to the molar 

 teeth, and the secretion is only evolved by their action; the probability is 

 that the incisor teeth, used in biting, and the interior of the mouth, are usu- 

 ally lubricated by the secretion of one or both of the other pairs of glands, 

 while the parotid glands are reserved for mastication alone. Goadbys Ani- 

 mal and Vegetable Physiology. 



ON THE FEEDING AND GROWTH OF THE AMERICAN ROBIN. 



At a recent meeting of the Boston Society of Natural History, a commu- 

 nication was read from Prof. Trcadwell, of Cambridge, giving a detailed 

 account of the feeding and growth of the American robin ( Turdus migrato- 

 rius, Linn.), during a period of thirty-two days, commencing from the 5th 

 of June. 



When caught, the two birds experimented on were quite young, their tail- 

 feathers being less than an inch long, and the weight of each about twenty- 

 five pennyweights, less than half the weight of the full-grown bird; both 

 were plump and vigorous, and had evidently been very recently turned out 

 of the nest. He began feeding them with earth-worms, giving three to each 

 bird that night ; the second day he gave them ten worms each, which they 

 ate ravenously; thinking this beyond what their parents could naturally 

 supply them with, he limited them to this allowance. On the third day, he 

 gave them eight worms each in the forenoon ; but in the afternoon he found 

 one becoming feeble, and it soon lost its strength, refused food, and died. 

 On opening it, he found the crop, gizzard, and intestines entirely empty, and 

 concluded, therefore, that it had died from want of sufficient food the effect 

 of hunger being perhaps increased by cold, as the thermometer was about 

 60. The other bird, still vigorous, he put in a warmer place, and increased 

 its food, giving it the third day fifteen worms, on the fourth day twenty -four, 

 on the fifth twenty-five, 011 the sixth thirty, and on the seventh thirty-one 

 worms. They seemed insufficient, and the bird appeared to be losing plump- 



