546 



Typhoid Fever 



2. This solution is added in quantities of o.i, 0.2, and 0.3 c.c. 



(delivered by means of a sterile graduated pipette to tubes, 

 each containing 10 c.c. of previously sterilized nutrient bouil- 

 lon). 



3. Incubate at 37 C. for forty-eight hours to eliminate contami- 



nated tubes. 



as recommended by Somers.* In these labyrinths the 

 motility of the organisms will separate the colon and 

 typhoid bacilli from non-motile organisms, and from those 

 less motile than themselves. The restraining medium pre- 

 vents the ready growth of most 

 organisms except colon and 

 typhoid bacilli. The anaerobic 

 conditions prevent the devel- 

 opment of aerobic organisms 

 which form the majority of 

 bacteria with which one comes 

 in contact in ordinary bac- 

 teriological examinations. The 

 typhoid bacillus, being more 

 motile than the colon, travels 

 more quickly through the coils 

 of the tube and first arrives 

 at its end, where it can be 

 found in pure or nearly pure 

 culture after about forty-eight 

 hours. 



Somers has improved the 

 instrument by bending it in a 

 circular form, so that it can 



stand alone, and by adapting its size to the Novy jar, so 

 that satisfactory anaerobic conditions can easily be attained. 

 Lofflerf has found malachite green a very useful adjunct 

 to our means of differentiating the typhoid from other simi- 

 lar bacilli. 



For the purpose 2^ to 3 per cent, of a 2 per cent, solution of malachite 

 green are added to the culture medium. The preparation given the 

 preference consists of i pound of meat macerated in i liter of water, 

 neutralized with potassium, with the addition of 2 per cent, of peptone, 5 

 per cent, of lactose, i per cent, of glucose, 0.5 per cent, of sodium sul- 

 phate, 2 per cent, of nitrate of potassium, and 3 per cent, of a 2 per cent, 

 solution of malachite green. 



* "Trans. Phila. Path. Soc.," 1906. 



t " Inst. hyg. Univers. Greifswald," see "Bull. Inst. Past.," iv, No. 9, 

 May 15, 1906, p. 393. 



Fig. 168. Starkey's labyrinth 

 as modified by Somers. 



