108 



On the Entomology of the 



[July 



or be found deficient, according to the richness or poverty of the soil, or 

 according as the degrees of heat and moisture influence the same. It 

 appears to me, that it is chiefly in swamps^, and in low and marshy lands 

 acted on by the rays of the sun, where there is a union of heat and 

 moisture, that the major part of Insects seem particularly to flourish. In 

 such localities we find genera more abundant, a great increase of 

 species, the number of individuals prodigiously augmented, and the 

 energies of life more rapidly developed. Animals appear more than 

 usually productive, either in the alluvium of mighty rivers, or in the 

 tropical jungle. It was on the banks of the Nile, amid its slime, acted 

 on by the influence of the sun, that the doctrine of spontaneous gene- 

 ration originated, and I am told also entertained by the ancient Brah- 

 mans on the banks of the Ganges, as seen in Susruta. It is in like 

 situations, where heat and moisture predominate, that nature still exhibits 

 her surpassing and inexhaustible fecundity. 



If we next turn our attention to the tropical jungle, we meet there 

 "with nearly an equally teeming exuberance and productiveness of species. 

 The heavy tropical rains saturating the accumulated mass of heated 

 leaves, and vegetable matter, considerable vapour is produced peculiarly 

 adapted to increase insect life ; and it is not a little singular, that as 

 soon as the first showers fall in these regions, all nature becomes reani- 

 mate ; and as the rains increase, so do the Insects in proportion more 

 and more, till the rainy season fairly sets in, at which period the jungle 

 and the forest literally teem with myriads of insect population, more 

 numerous than the stars of heaven, and as countless us the sands of 

 the sea-shore. In concluding this part of my subject, I need only re- 

 peat shortly, that heat and moisture combined, exercise a powerful con- 

 trol over the geographical distribution of insect life, and that this dis- 

 tribution is also influenced in a greater or less degiee by vegetation, 

 as well as by the soil of a country ; but these are subjects which require 

 further elucidation. 



INFLUENCE OF VEGETATION. 



The entomologist who wishes for accurate information respecting the 

 geographical distribution of Insects over the wide extent of our globe, 

 must take into his consideration l ot only the influence of temperature, 

 but that of vegetation ; nor should he omit to note the varieties of soil 

 which materially influence it. The dependence of this distribution of 

 animals, although greatly swayed by temperature, is no less so bv the 

 supply of food and nourishment they can ^ btain. Insects are designat-« 

 ed according to the kind of food they consume, as carnivorous or phy- 



