FECUNDITY OF INSECTS AND FISHES. 47 



only deposits two egs;s ; while a sinpjle plant-louse 

 (^Aphis)^ as we mentioned before from Rt?aiimur, 

 may be the living progenitor of 5,904,900,000 de- 

 scendants, and the queen of the warrior white ants 

 (Termesbellicosus^S^iEXinm.) produces 31,536,000 

 eggs in one year. 



We may illustrate this subject by an extract exem- 

 plifying the proportionate fecundity of the animal king- 

 dom in general. " Compared with the rest of ani- 

 mated nature," says Dalyell, " infusion animalcula 

 are surely the most numerous : next are worms, in- 

 sects, or fishes ; amphibia and serpents, birds, quad- 

 rupeds ; and last is man. The human female produces 

 only one at a time, that after a considerable interval 

 from birth, and but few during her whole existence. 

 Many quadrupeds are subject to similar laws ; some 

 are more fertile, and their fecundity is little, if at all, 

 inferior to that of certain birds, for they will produce 

 ten or twenty at once. Several birds will breed fre- 

 quently in a year, and have more than a single Qg^ 

 at a time. How prodigious is the ditFerence, on de- 

 scending to fishes, amphibia, reptiles, insects, and 

 worms ! Yet among them the numbers cannot be 

 more different. According to naturalists, a scorpion 

 will produce sixty-five young ; a common fly will lay 

 144 eggs; a leech, 150 ; and a spider, 170, I have 

 seen a hydrachna produce 600 eggs, and a female 

 moth 1 100. A tortoise, it is said, will lay 1000 eggs, 

 and a frog 1100. A gall-insect has laid 5000 eggs; 

 a shrimp, 6000 ; and 10,000 have been found in the 

 ovary, or what is supposed to be that part, of an 

 ascarides. One naturalist found above 12,000 eggs 

 in a lobster, and another above 21,000. An insect 

 very similar to an ant {Mutilla?) has produced 

 80,000 in a single day ; and Leeuwenhoeck seems 

 to compute four milHons in a crab. Many fishes, 

 and those which in some countries seldom occur 



