INFECTIOUS DISEASES AND MICROBES, ETC. 221 



in the lymphoid follicles of the intestine in fatal 

 cases. Sometimes the microbe is present in "the 

 kidneys and urine. Bacilhis typhosus measures 

 from 2 to 3 ft long, and from 0*3 to 0'5 //, wide ; and 

 it forms filaments which sometimes measure 50 //, 

 in length. It (Fig. 33, 4) has rounded ends ; and 

 it has been stated that spore -formation takes place 

 at the extremities of the rods. This statement is, 

 however, doubted by some bacteriologists; because 

 the so-called spores have never been observed to 

 germinate, etc. B. typhosus grows on bouillon, 

 nutrient gelatine, 1 steamed potatoes (at 37C.), and 

 blood serum ; and it can grow either in the presence 

 or in the absence of free oxygen. On gelatine- 

 plates, the microbe gives rise to greyish colonies 

 with irregular margins, without liquefying the gela- 

 tine. In tube-cultivations, a growth appears as a 

 bluish-grey film on the surface, whilst 'in the 

 needle track there is a delicate zone of the same 

 bluish-grey colour, surrounded in turn by a peculiar 

 opalescent milkiness. The most characteristic 

 growth, however, occurs on sterilised potatoes. It 

 is characteristic in that, even when there is a most 

 luxuriant growth of the typhoid bacillus, it cannot 

 be recognised by the naked eye, even at the end of 

 three or four days, except by a peculiar moist ap- 

 pearance of the potato, which, taken along with the 

 appearances in milk and on gelatine, so far as is at 

 present known, distinguishes the growth of this 

 microbe from all others. It will be remembered, 

 however, that the potato is slightly acid ; and it 



1 Gaffky in Mitth. aus dem. k. Getundheitsamte, 1886. 



