426 BAGTERWLOOY. 



sharply defined seat of growth. If a mixture of the 

 two organisms be taken upon the point of a needle and 

 deposited at a single spot upon a plate made from a 

 semi-solid nutrient medium, or be planted as a stab- 

 culture in a test-tube of the same medium, the growth 

 of the colon bacillus remains about the part touched, or 

 along the track of the needle, while that of the typhoid 

 bacillus spreads as a delicate cloud for some distance 

 beyond. The medium recommended by Stoddart for 

 the test is a mixture of equal parts of ordinary meat- 

 infusion — peptone-agar-agar (1 per cent, agar-agar) and 

 meat-infusion-peptone-gelatin (10 per cent, gelatin). 

 In this mixture the proportion of agar-agar present is, 

 obviously, 0.5 per cent., and that of the gelatin 5 per 

 cent. These amounts are sufficient to keep it just about 

 solid when exposed to 35° C. 



A limited experience with the method leads us to 

 regard it as a useful addition to our- means for the iso- 

 lation and identification of the typhoid and typhoid-like 

 bacilli. It is not infallible in its indications. 



It is employed in two ways — for plates and for tube 

 cultures, though the former is perhaps the more useful. 

 Here the liquefied culture mixture is poured into a ster- 

 ile Petri dish and allowed to gelatinize ; after which it 

 is inoculated at a single point, or at several points, with 

 the pure culture, or with the mixture of organisms to 

 be tested, and placed at 35° C. The characteristics of 

 the growths of the typhoid and of the colon bacillus 

 are given above.^ 



Hiss's method. A short time subsequent to Stoddart's 

 publication Hiss called attention to a similar application 



' For further details, see Stoddart : Jo'jrnal of Pathplogjr au^ SSS' 

 teriology, 1897, vol. iv. p. 429. 



