(2) Efficient sterilization of all vessels by steam if possible, or by abundance of boiling water.
In cases where the water supply is known to be infected, or even where it is merely doubtful, it is wise to have recourse to sterilization by boiling, rather than trust to any filter.
Subjection to the temperature of boiling water for, say, half an hour seemed an efficient mode of sterilization, until it was discovered that the spores of bacteria are so involved in heat-resisting membranes, that only prolonged exposure to dry, baking heat can be recognized as an efficient process of sterilization.
Chemical methods of sterilization have also been suggested, depending on the use of iodine, chlorine, bromine, ozone, potassium permanganate, copper sulphate or chloride and ()their substances.
This method of intermittent sterilization originated with Tyndall, and it was an important contribution to biological science and industrial practice.
They found that the germ of tetanus had been introduced into the fluid before the bottle was opened at Malkowal, and they thought it probable that this might have occurred owing either to insufficient sterilization or to the process of filling the bottle from a larger flask having been performed with defective precautions.
Both these filters arrest the organisms by purely mechanical action, and if the joints are water-tight and they receive proper attention and frequent sterilization, they both give satisfactory results on a small scale for domestic purposes.
The nature of sterilization, and the difficulties in securing it, as well as the extreme delicacy of the manipulations necessary, made it possible for a very long time to be doubtful as to the application of the phrase omne vivum e vivo to the microscopic world, and there still remain a few belated supporters of abiogenesis.
The spore-bearing generation may throughout its phylogenetic history have been independent at one part of its life, and have been derived by modification of individuals homologous with those of the sexual generation, and not by the progressive sterilization of a structure the whole of which was originally devoted to asexual reproduction.
It is only necessary to bear in mind the great part played by sterilization in the laboratory, and pasteurization on the fermentation industries and in the preservation of food materials.
Sterilization then becomes an easier task, the milk drawn under these conditions being very poor in spore-forming bacteria.
These are discussed by Mr Howard in the paper referred to, but in brief they all amount to measures of general hygiene, and the isolation, prompt removal, or proper sterilization of the animal or human excrement in which these flies breed.