GENERATION OF INSECTS. 15 



to the nurseries. The extraordinary labour which this 

 requires in the community may be understood, when, 

 according to Smeathman, she lays 60 eggs in a minute, 

 which will amount to 86,400 in a day, and 31,536,000 

 in a year. The exceptions now mentioned, howev- 

 er, do not in the least invalidate our general posi- 

 tion. 



Cell of a queen of the Termites bellicosi, broken open in front ; the 

 labourers surrounding the queen and carrying off her eggs. 



Another no less remarkable circumstance is the 

 great weight, or specific gravity, of the eggs of in- 

 sects. From numerous experiments we may venture 

 to say that those of all the species which we have 

 tried sink rapidly in water the moment they are 

 thrown into it, from the egg of the drinker moth (Odo- 

 nestis Potatoria, GERMAR), which is nearly as large 

 as a hemp-seed, to that of the rose-plant louse (Aphis 

 rosce\ which is so small as to be barely visible to the 

 naked eye. Some eggs of the gipsey moth (Hypo- 

 gymna dispar, STEPHENS), indeed, floated in water, 

 because they were covered with down. It is well 

 known, as we shall presently show, that the diffu- 

 sion of many of the seeds of plants is accomplished 

 by the winged down with which they are clothed; 



