The Balance of Nature 303 



at the bottom of the water, and fishes, and birds, that swim 

 and dive in it, will be engaged in devouring them, at all 

 stages, and at almost every turn. Nature, truly, looks after 

 her children ; but the form her care takes, in regard to some 

 of them, is that they are so uncountably prolific that no 

 amount of killing is able to reduce their numbers ! She 

 holds her balance even, but with, apparently, no thought 

 for the individual, and of all her creatures has endowed 

 but one with power to upset it ; He, with his " reason," is 

 permitted, by pollution of the water, by draining it away, 

 or otherwise, for his profit or his pleasure, to sweep away 

 whole legions of life in one disastrous swoop, while Dame 

 Nature stands idly by, smiling on the exhibition of the skill 

 of her most perfect production. Perhaps, having accom- 

 plished his ends, he may wish to bring back the teeming 

 multitudes of ephemeridae, to provide food for his reintro- 

 duced fishes, and then comes the rub ! If he has destroyed, 

 in a span, what has been developed through countless eons, 

 need he wonder if his efforts prove unavailing to restore 

 the balance in the space of a short lifetime ? Or if he has 

 gone to war without counting the cost, should he grumble 

 at the day of reckoning ? In her slow but certain methods, 

 Nature provided an ample food supply for each predatory 

 creature before the latter was introduced upon the scene ; 

 but once let that supply be unduly encroached upon, and it 

 is no easy task for poor mortal to restore it. 



The little Cloeon, in its first winged state, is of a nearly 

 uniform pearly grey colour, with a slightly milky or opaque 

 appearance. After its final metamorphosis, it becomes paler, 

 and almost transparent, save for a patch of bright brown on 

 the thorax, a spot of similar colour near the tail, and darkish 

 legs. The tail is bifurcated, and considerably longer in the 

 perfect insect than in the pseudimago. It continues upon 

 the wing for some days, the life of the pregnant female 

 exceeding that of her consort ; and, like so many other 

 small insects, the males in a dancing flock seem always 

 vastly to outnumber the females. Perhaps this may, to 

 some extent, be due to the fact of the female, as being the 

 more valuable of the two for the continuance of the race. 



