CHAPTER X. 



Wonderful economy of insects and animalcules— Compensation 

 we receive from insects for their injuries — Commercial im- 

 portance of insects— their uses in removing decaying organic 

 matter — Adaptation to this object — Reasons of insect trans- 

 formations — Their amazing multiplication — Larva state — 

 Perfect condition — Different habitations of the same insect in 

 its different states — Injuries to our crops from insects — Wire- 

 worms — Elaters — Weevil — Oscinis vastator — Cephus pyg- 

 maeus, or corn saw-fly— Thrips — Plant-lice — Palliatives all 

 we can expect — Mistakes as to remedies arising out of want 

 of knowledge — Infusorial animalcules — View of them by the 

 microscope in infusions easily made — Polygastrica— Specula- 

 tions— Diffusion of the eggs — Curious forms of infusoria — 

 Ehrenberg — Cilia and their uses — Monads — Fossil infusoria^ 

 Prevalence of living infusoria — Their multitudes — Proved by 

 experiments to emit oxygen — Liebig — Guano— Uses of infu- 

 sorial animalcules — Source of pure vital air — Limit putrefac- 

 tion — Destroyed by putrescent matters and sulphuric acid- 

 Concluding remarks. 



The economy of the minutest insects and 

 animalcules with which we are acquainted is 

 quite as wonderful as the nature of the fungi 

 adverted to in the preceding chapter ; while 

 some experiments recently made on the infu- 

 soria, to which class the little eels of the pep- 

 per-corn of the wheat belong, are as striking 



