The theory and practice of hygiene (Notter and Firth) / by J. Lane Notter ... and W. H. Horrocks.

  • Notter, J. L. (James Lane), 1843-1923.
Date:
1900
Catalogue details

Licence: In copyright

Credit: The theory and practice of hygiene (Notter and Firth) / by J. Lane Notter ... and W. H. Horrocks. Source: Wellcome Collection.

Provider: This material has been provided by London School of Hygiene & Tropical Medicine Library & Archives Service. The original may be consulted at London School of Hygiene & Tropical Medicine Library & Archives Service.

    139/1146 (page 113)
    no gas formation. Potato, a dirty white growth. Nitrate hroth, shght reducing action. Peptone, no indol produced. Microscopical cliaracters.—K small, round-ended bacillus, often in pairs and looking like a diplococcus. It is motile, and does not grow well at 37° C This organism closely resembles the B. albus of Eisenbero-. The B. ubiguitus of Jordan belongs to this group, but differs from the type by coagulating milk. Another organism has frequently been found which resembles the type in most of its cultures, but differs from it by grow- ing well at 37° C, and producing gas in glucose-media. Class II. Tliis class contains the micro-organisms which are common in sewao-e but are rarely, if ever, found in pure water-supplies. Many of them are derived from the intestinal canal of human beings and aiumals ; others are associated with putrefactive processes. The recognition and proper inter- pretation of these organisms is a matter of the first importance. It often happens during the examination of water-supplies, suspected to have caused zymotic disease, that chemical analysis, enumeration of micro-organisms, and search for pathogenic organisms all fail to give any sufficient data upon which a reliable opinion may be based as to the possibility of contamination. Under these conditions the detection of the organisms in this class will either enable a proper decision to be made or suggest a rigid examination of the source of supply, when possibly unsuspected means of contamination will be discovered. The most important organism in this class is the Bacillus coll, which may be said to be the sheet-anchor of the water bacteriologist. Studies of sewage and normal fseces, however, have shown that the B. coli usually described in the text-books is the type of a laro-e group containing many varieties; and it is the proper interpretation of these varieties which causes so much difficulty at the present day. The Bacillus coli communis is usually described as follows: Colonies on gelatine plates.—In the depth the colonies are circular or oval in shape and dark brown in colour. On the surface after twenty-four to forty-eight hours they appear as thin bluish-gi-ey transparent films with an irregular margm ; under a low power they sometimes resemble flakes of glass with faint surface markings, but more commonly they appear somewhat opaque Avith a faint yellowish-brown colour and show tracings of ridges and depres- sions running from the centre to the periphery; at times wavy lines paraUel to the margin are seen. The gelatine is not liquefied. Gelatine stab.—On tlie surface an expansion appears like the colonies just described ; alon the stab there is white growth. Agar, thick white growth. Potato.—As a rule a thick brownish-yellow growth is produced; occasionally the growth is an almost transparent film like that of B. typhosus. Milk, generally coagulated in twenty-four to forty-eight liours at 37° C.; the whey is markedly acid. Grlucose gelatine, abundant gas formation in twenty-four hours at 22°C Peptone and salt sohition.—Indol reaction always given after seven days at iJ7 0.; very often the reaction is obtained after forty-eight hours Broth rendered turbid in twenty-four hours at 37°C.; later, a slight film forms on the surface. Gelatine (25 per cent.).—At 37°C. a distinct white thick fihn appears on the surface. Microscopical characters.—It usually appears as a very short bacillus, often strongly resembling a coccus, but longer forms are often seen m old cultures. As regards motility it varies considerably ; sometimes it is almost motionless, at other times it appears to be as motile as tlie B. typhosus. As a rule it possesses from .one to three, flagella, which are very brittle and H