164 REPTILES OF THE WORLD 



for a good ten minutes. During this time the grinding 

 motions of the jaws show a vicious desire to imbed the 

 fangs as deeply as possible. 



Within a few weeks of captivity, Gila Monsters be- 

 come reasonably tame. For a while, however, they can- 

 not be trusted, nervously turning their heads if startled 

 in what might be termed involuntary preparations to 

 bite. After a few months this nervousness wears away, 

 when they are the personification of good nature, permit- 

 ting themselves to be handled in the most unceremonious 

 fashion, without the least show of temper. A warm 

 sand bank, in undiluted out-door sunshine, produces 

 curious psychological phenomena. If left in a place 

 like this for a few minutes they become different crea- 

 tures, fiercely snapping from side to side, resenting the 

 least hint of interference with sharp hisses, while they 

 keep their jaws gaping, ready to close upon anything 

 coming within reach. Several times when the writer 

 wished to extract poison from his specimens, he has been 

 unable to induce them to bite until they had a sun-bath 

 on a warm sand bank. Then they bit with such energy 

 it was difficult to disengage their jaws from the vessel 

 in which the venom was collected. Curiously enough, 

 the temperature outside differed little from that of their 

 artificially warmed cage. It is the sunlight which ap- 

 pears to produce the exhilarating effects. 



In experimenting with the venom we find it dries and 

 cracks in the same fashion peculiar to snake poison. 

 Small animals injected with it die quickly, the poison 

 appearing to particularly attack the heart. From the 

 symptoms the animals displaj^ it is well to rate this 

 species as among the reptiles highly dangerous to man. 



The Gila Monster is an oviparous lizard, depositing 

 smooth, tough-shelled white eggs that are large in pro- 



