A note on the M'Fadyean staining reaction for anthrax bacilli / by J.D.E. Holmes.

  • Holmes, John Dalrymple Edgar, 1867-
Date:
1913
Catalogue details

Licence: In copyright

Credit: A note on the M'Fadyean staining reaction for anthrax bacilli / by J.D.E. Holmes. 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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    turOj the slide is fixed, by hjwering’ it, film side upwards, into the Hame of a Bunsen burner, for a second. Repeat this three times, or until the under surface of the gdass is a little too hot to he borne by the shin of the palm of the hand. Particular attention should he paid to the process of fixation, as the violet reaction is obtained only when the preparation is imperfectlp fixed. M^Fadyean draws special attention to this. -'It is Important to notice that what might he thought trivial departures from the directions given above will entirely prevent one from obtaining the reaction. For instance, if the film he fixed with sublimate formalin or osmic acid solutions, no trace of tlie violet reaction will he obtained. Failure av ill also occur if, in fixing the film by dry heat, the temperature is allowed to rise as high as 1 50°C. 100°C is sutficieut, and it should not be allowed to rise much above that. Again, the film ought not to he very thin. Partly for this reason, and partly because of over-heating in the Bunsen flame, such thin films as are obtained by pressing two cover glasses together, generally fail to show the violet reaction. As an alternative method of fixation, the slides or cover glasses carrying the dried films may he immersed for a few minutes in absolute alcohol or methylated s}>irit. The stain must not he applied to the hot slide, or heated until the steam begins to rise, as is recommended for some methods of staining, nor must the preparation he washed in alcohol after staining.^'’ It is also necessary to be careful that the stain is lightly washed off and that no pressure is used wheir drying the film between alisorhent paper. The violet stained amorphous granules of the capsule, being imperfectly fixed, are easily removed from the film, and rough handling in washing or drying may cause an apparent failure to obtain the reac- tion. As regards the stain, M’Fadyean was, at first, of opinion that it was necessary to use a 1 per cent, solution of methylene blue which had been in stock for some time and thus acquired a polychromatic quality, or that it was necessary to add a t per cent, bicarbonate of soda to a freshly prepared 1 per cent, solution of Grubler’s powder. Subsequently, it was found that freshly prepared, pure medicinal methylene blue gave the reaction, ovlthout the addition of bicarbonate of soda. For some years [>ast T have made use of the violet reaction in the diagnosis of anthrax, and have never failed to obtain a positive result, in anthrax blood, when the above directions have been carefully adhered to. I have used it in summer and ivinter temperature, both on the hills and on the plains in India, and found no variation.