140 The Naturalist in La Plata. 



flowers." If this be so, it is quite certain that the 

 juices fail to satisfy them ; and that, like Dr. Tanner, 

 who was ravenously hungry during his forty days' 

 fast, in spite of his frequent sips of water, the 

 mosquito still craves for something better than a 

 cool vegetarian diet. I cannot help thinking, 

 though the idea may seem fanciful, that mosquitoes 

 feed on nothing. "We know that the ephemerae take 

 no refreshment in the imago state, the mouth being 

 aborted or atrophied in these short-lived creatures ; 

 but we also know that they belong to an exceed- 

 ingly ancient tribe, and possibly, after the earth 

 had ceased to produce their proper nourishment 

 there came in their history a long hungry period, 

 which did not kill them, but lasted until their 

 feeding instincts became obsolete, the mouth lost 

 its use, and their life in its perfect state dwindled 

 to its present length. 



In any case, how unsatisfactory is the mosquitoes' 

 existence, and what a curious position they occupy 

 in nature ! Let us suppose that, owing to some 

 great change in the conditions of the earth, rapacious 

 birds were no longer able to capture prey, and that, 

 by a corresponding change in their organizations, 

 they were able to subsist on the air they breathed, 

 with perhaps an occasional green leaf and a sip of 

 water, and yet retained the old craving for solid 

 food, and the old predatory instincts and powers 

 undiminished ; they would be in the position of 

 mosquitoes in the imago state. And if then fifty 

 or a hundred individuals were to succeed every 

 year in capturing something and making one hearty 

 meal, these few fortunate diners would bear about 



