398 POPULAR SCIENCE MONTHLY. 



The bifid extremity of their tongues, soft and always moist, is 

 most probably an organ delicate to touch and probably to taste. 

 They never cease to project it forward on to all the things within 

 their reach, and although accustomed to meal worms, they begin 

 generally by feeling them at least the first one in this way be- 

 fore taking them. The whip-tails { Uromastix) do the same, and 

 when set down in the grass test all the flowers with their tongue. 

 I should observe further that these animals did not hibernate 

 with me, and that they were as lively and active in winter as in 

 summer. The same may be said of two jerboas which I kept in 

 captivity for three years and a half. Hibernation, therefore, does 

 not seem to be a iDhysiological necessity, but to be rather a natu- 

 ral effect of the cold, like the depression of the thermometer. The 

 lizards were very fond of keeping themselves in front of the 

 registers. 



I now come to a trait which on reflection ai)pears to me to be 

 characteristic in the highest degree. Jealousy is a feeling not 

 less natural to animals than to us. The males compete in 

 strength, beauty, or talent to conquer the females. Beasts of 

 prey, from spiders to lions and eagles, enforce respect of their 

 hunting grounds. All defend their bed, their burrow, or their 

 nest ; and probably, too, herbivorous animals living in herds do 

 not permit other herds to trespass upon their pastures. The jeal- 

 ousy of the dog is well known ; if he is left alone, he will eat the 

 part of the cat, and even rob the pigs of their messes. I have 

 kept two jerboas for three years, all very familiar. Every even- 

 ing we give each of them an almond, which they come and take 

 out of the hand, and even ask for. But hardly has one received 

 hers than, without paying any more attention to us, the other 

 pursues her, takes it away from her, and a struggle ensues a 

 struggle which is otherwise courteous. The same play is acted 

 when dandelions are given to them ; hardly has one detached a 

 leaf when the other tries to snatch it from her. 



My lizards did not vary from the general rule. The best worm 

 was always the one that a comrade had. If it was long, we might 

 witness such a steeplechase as is seen sometimes in poultry yards. 



Pedro was jealous of my preference and caresses. When he 

 was on my sleeve, I could keep him for hours motionless by pass- 

 ing my hand lightly along his body ; but if I took Pierre or an- 

 other lizard up, his rage broke out at once, and he would jump 

 upon him with his mouth menacingly wide open. If, however, 

 I chose the large lizard, he gradually drew back, as if regret- 

 fully, without leaving me. Now, what good do caresses do to a 

 lizard ? Dogs and cats, they tell us, are delighted with them. But 

 these animals, when they were young, were caressed by their 

 mothers, who licked, bit, and amused them, and it is not strange 



