Upon an anti-cholera serum / by Allan Macfadyen.

  • Macfayden, Allan, 1860-1907.
Date:
[1906]
Catalogue details

Licence: In copyright

Credit: Upon an anti-cholera serum / by Allan Macfadyen. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    growth was made, which was then washed in a high-speed centrifuge. The separated organisms were triturated at the temperature of liquid air and the product was taken up in 1 in 1000 caustic potash. On spinning, a clear supernatant fluid representing a 10 per cent, extract of the comma bacilli was obtained and was treated very rapidly with chloroform vapour. The cell juices were in every instance sterile and were acutely toxic to experimental animals. The quantita- tive yield from the various grinds was remarkably constant and averaged about ten milligrammes of solid matter per cubic centimetre of the juices. This being the case it was possible to trace any parallelism that might exist between the virulence and the toxicity of the cultures—a matter of considerable theoretical and practical importance. It may be here stated that the cultures of high virulence yielded the most toxic and the cultures of low virulence the least toxic juices, whilst in those instances in which the virulence had been allowed to diminish to such an extent that, e.g., two platinum loops of a culture did not kill the guinea-pig, the toxicity of the juice suffered a corresponding drop, one-half cubic centimetre and even one cubic centimetre failing to kill, whilst one-tenth cubic centimetre from a virulent culture killed acutely. This leads me to conclude that as regards the cholera endotoxin virulence and toxicity are intimately related, inasmuch as increased virulence implies increased toxicity and vice versa. This observation may explain the discrepant results obtained by different workers and in any case justifies the use I have constantly made of virulent cultures in my investigations upon this and other pathogenic organisms. The variations in toxicity of the cholera cell juices I con- sider to have been largely dependent on variations in the toxic quality of the material at the time of grinding. The index for a good yield of endotoxin is the virulence of the given culture and this varies under laboratory conditions despite all precautions taken, and is liable to sudden drops. It is a source of trouble in connexion with experimental work on the cholera organism. Toxioity of the cell juices.—From the most virulent cultures toxic extracts were obtained which on peritoneal injection killed guinea-pigs acutely in doses of r'0th and 2’uth cubic centimetre, whilst s'0th cubic centimetre rendered the animals ill. The average lethal dose for guinea-pigs of 300 grammes weight was T'0th cubic centimetre (about one milligramme). The extracts from cultures of lower virulence killed in doses of 0 • 3 and 0 • 5 cubic centimetre. Where the virulence was feeble doses of 0-5 cubic centimetre and upwards were necessary to kill the animals. The endotoxin also acted sub-