TEXT-BOOK OF BACTERIOLOGY. 297 



occur in dense out not numerous heaps. The latter might easily be 

 overlooked on observing them with immersion, for which reason it 

 is better to search for them with a low power ; they will then appear 

 detached from their surroundings as stronger- colored deep-blue 

 and opaque spots. If we examine them with tha immersion lens, 

 they appear as irregularly -circumscribed foci of radiating or net- 

 shaped composition, so tightly joined together in the middle that 

 they can be recognized as single rods only toward the border. 



In order to facilitate the demonstration of bacilli, E. Fraenkel 

 has recommended wrapping the organs in cloths soaked in sub- 

 limate solution and preserving them for some time (up to three 

 days) after death at a high room temperature, because under these 

 conditions, if not an increase, at least a far more vigorous develop- 

 ment of the bacillus foci takes place, for instance, in spleen and liver. 



Quite recent cases of the disease are best for investigation, pre- 

 vious to the formation of ulcers and the decay of the tissue in 

 which the bacilli perish likewise. There may then be noticed nu- 

 merous foci of bacteria in the pulpy, swollen patches and glands; 

 the rods will be recognized later only in the deeper, non-necrotic 

 part of the real mucous membrane, in the mucosa and inter- 

 muscularis below the ulcers. About a dozen sections of spleen and 

 liver may have to be examined before we arrive at any result and 

 discover the bacillus heaps in their special arrangement. The 

 bacteria have (besides the tissue of the internal organs) been ob- 

 served in the albuminous and even in the non- albuminous urine 

 of very sick persons, and they have even been seen (according to 

 Neumann) to appear there in especially large quantities. In the 

 blood, too, their presence has been ascertamed, and they were like- 

 wise found by different examiners in the dejections of patients. 



Typhoid fever is one of those affections in which the co-opera- 

 tion of several diverse micro-organisms can frequently be estab- 

 lished. The first original bacterium calls forth a number of 

 morbid symptoms, changes in the tissue, etc., which constitute a 

 proper soil for the subsequent settlement of some secondary 

 causes of infection. The morbid picture stands then under the in- 

 fluence of the common activity of both, and we have to deal with a 

 genuine mixed infection. The new micro-organism may finally 

 push the original one so far in the background that it presides ex- 

 clusively over the scene. 



They are usually streptococci which go hand in hand with the 

 other bacteria and move under their guidance into the diseased 

 organism. In typhoid, too, are regularly found such chain- forming 

 micrococci in the tissue of the spleen or liver or intestinal wall, etc. 



