PROCEEDS FRO]M LIFE. 279 



is true that beings of that kind often appear under 

 circumstances where we cannot trace the steps. 

 When any organic matter begins to be disorgan- 

 ized, or as we say, begins to putrify or rot, we 

 always find that, if it is exposed to the air, or if 

 the air has access to it, under circumstances fa- 

 vourable to the growth of organic beings, those 

 beings, varying in kind with the decaying sub- 

 stance, are found upon it and supporting them- 

 selves on its substance. Some of these, even 

 when they have attained their full size, are so 

 small that the eye cannot distinguish the indivi- 

 duals ; and they are often found in places to which 

 we can trace no visible opening. But still they 

 never make their appearance except in situations 

 favourable to their growth. When the bodies of 

 large animals are left dead upon the surface of the 

 earth, or buried at a small distance under it, in 

 warm weather, they are very soon found full of 

 maggots. But even with that small difference in 

 the circumstances, there is a difference in the 

 maggots. Above ground they are the larva of 

 air-flies ; but if below ground, they are the larva 

 of beetles. If, too, before they have been affected 

 by any thing else, the bodies are buried to a great 

 depth in the earth, or if they are far in the sand, 

 or covered with quick-lime, or coated with any of 

 the pungent resins, which are hurtful to most of 

 the minute animals, maggots do not make their 

 appearance. As little do they appear when the 

 body is under water; for, so far as we know, 

 though there are many small animals that will 

 prey on the carcases of land animals when depo- 

 sited there, there are none that place their eggs 

 in those bodies for the purpose of being hatched. 

 B b 2 



