A manual of veterinary hygiene / by F. Smith.

  • Smith, F. (Frederick), Sir, 1857-1929.
Date:
1893
Catalogue details

Licence: Public Domain Mark

Credit: A manual of veterinary hygiene / by F. Smith. Source: Wellcome Collection.

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    water from the physical examination alone might be mis leading, as a very unpromising looking water may be perfectly pure, and vice vend. We are, however, justified in considering, in the absence of anything more definite, that a water possessing no colour, taste, or smell, with but a slight sediment and brilliant lustre, is perfectly fit for drinking purposes. The object of a microscopical examination of water is to determine the nature of the suspended matter. This, as we before stated, is organic and inorganic ; vegetable matter, dead or living; animal matter, as epithelium, hairs, portions of tissue, ova of insects or parasites ; also those organic substances which lie between the animal and vegetable kingdom, as bacteria, vibriones, etc. ; inorganic substances, as sand, chalk, and other mineral matter. The indication which these substances afford, particularly the organic, is evidence of pollution. Respecting the innumerable living organisms which may be found, it is difficult to say that these are direct evidence of pollution, for algae, diatomes, and desmids are found in most running streams. Much larger organisms, as the water-flea, are probably quite harmless in themselves, though for all we know they may be the intermediate bearers of certain parasites. Re- specting the latter, there can be no doubt that many forms of parasite are conveyed through the ova being in the drinking water. The filaria which affects the blood of man develops in water within the body of the mosquito, and in the relapsing fever of equines, described by Mr. J. H. Steel as produced by a spirillum, there was certain evidence to point to the drinking water as the source of the organism. It should be clearly understood that in all analyses of water the dissolved solids only are referred to; all suspended
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