138 The Naiuralist in La Plata. 
insects have certainly had ample time in which to 
learn well at least one lesson. 
There is not in all organic nature, to my mind, 
any instance of wasted energy comparable in 
magnitude with the mosquito’s thirst for blood, and 
the instincts and elaborate blood-pumping apparatus 
with which it is related. The amount of pollen 
given off by some wind-fertilized trees — so great in 
some places that it covers hundreds of square miles 
of earth and w^ater with a film of yellow dust — • 
strikes us as an amazing waste of material on the 
part of nature ; but in these cases we readily see 
that this excessive prodigality is necessary to con- 
tinue the species, and that a sufficient number of 
flowers would not be impregnated unless the entire 
trees were bathed for days in the fertilizing cloud, 
in which only one out of many millions of floating 
particles can ever hit the mark. The mosquito is 
able to procreate without ever satisfying its ravenous 
appetite for blood. To swell its grey thread-like 
abdomen to a coral bead is a delight to the insect, 
but not necessary to its existence, like food and 
water to ours ; it is the great prize in the lottery 
of life, which few can ever succeed in drawing. In 
a hot summer, when one has ridden perhaps for 
half a day over a low-lying or wet district, through 
an atmosphere literally obscured with a fog of 
mosquitoes, this fact strikes the mind very forcibly, 
for in such places it frequently is the case that 
mammals do not exist, or are exceedingly rare. In 
Europe it is different. There, as Reaumur said, 
possibly one gnat in every hundred may be able to 
