THE ORIGIN OF THE VOICE 15 



the movements of the lungs ; and if the animals 

 were of large size, a kind of snorting, like that 

 of a horse, might thereby be produced ; or perhaps 

 the initial movement of certain limbs, like the 

 twitching of the wings of a terrified falcon, would 

 be occasioned. The development of clear cries 

 from snorts or grunts must be regarded as a pro- 

 cess of very slow progress. But we must remember 

 that there are several widely distinct races of 

 animals whose only attempt at vocal utterance is 

 the employment of a yet simpler mode of expres- 

 sion — a mere puff or hiss caused by the toneless 

 expulsion of air from the lungs ; and be it observed 

 that in these instances, as well as in those of its 

 occurrence in animals possessing voices, the sound is 

 invariably due to anger or to fear. The common 

 tortoise, so often kept as a pet in English gardens, 

 when suddenly alarmed withdraws its head and 

 limbs rapidly within its shell, and at the same 

 time a kind of short hiss is heard, especially if 

 the animal has been frightened by being grasped 

 in the hand. In serpents, a hiss is the common 

 expression of anger. Among birds, the same feel- 

 ing is sometimes expressed in a similar tone, but it 

 is rarely employed except by birds sitting on their 

 nests. In this position, the female nuthatch, the 



