60 HEALTH AND DISEASE 



Staining. — Although the organism is readily seen without being first 

 stained, some may prefer to stain it, and we therefore give the most easy 

 and at the same time most effectual method of carrying out this procedure. 



" Make a thin smear of pus from the suspected wound, ulcer, or pustule 

 on a cover glass or slide, fix it in the ordinary manner by passing it three 

 times through the flame, and then proceed to stain with the following 

 preparation : — 



Nicolle's Violet, saturated solution of gentian violet in 90 per cent of alcohol, 10 cc. 

 One per cent Aqueous Solution of Carbolic Acid, 100 cc. 



" Leave the .stain on for about five minutes, then run it off, removing the 

 superfluous .stain by waving it for a moment or two in water, and put on: — 

 Grammes Iodine Solution — 



Iodine 1 part 



Iodide of Potassium ... ... ... 2 parts 



Distilled Water 300 „ 



"This fixes the stain in the organism. After leaving it in for two 

 or three minutes run it off and treat with alcohol, which takes the stain 

 out of everything except the various organisms which have taken it up, 

 in fact it will begin to remove it from the cryptococci also if left on 

 for more than a few seconds. 



" Having now decolorized put on the following counter stain : — 

 Saturated Solution of Vesuvine (Bismai-ck Brown), 



and after having left it on for about three minutes run it off, wash in 

 water, and dry. The specimen is now ready to be examined under the 

 microscope, or may be mounted in Canada Balsam." (Pallin.) 



Causes. — Any wound on any part of the surface of the body with 

 which the virus may be brought into contact offers an opportunity for 

 infection. A brush on the fetlock joint or a crack in the heel will 

 account for its ofttimes occurrence on the hind limbs, a broken knee or 

 a less marked injury to some other part suffices to explain its less frequent 

 occurrence in the fore-legs. Injury to the face, the poll, the withers, or 

 back by the harness will expose the animal to infection, as will also 

 wounds following upon castration and breaking of abscesses in strangles. 



Zoological Distribution. — Although solipeds would appear to be 

 the only animals affected l)y it, it has been said to have occurred in 

 cattle, and in referring to this Pallin remarks: "Care .should be taken 

 not to confound it with a disease found among the cattle in Guadeloupe 

 known under the name farcin de hceuf, and due to a bacillus discovered 

 by Nocard, and which MetschnikofF describes as a streptothrix. This 



