584 BACTERIA IN INFECTIOUS DISEASES. 



iments upon animals and by the demonstrated fact that retention of 

 urine per se does not give rise to inflammation of the bladder. But 

 this is not the only microorganism which is capable of causing a 

 cystitis when introduced into a bladder which has suffered some kind 

 of mechanical injury or has been subjected to the action of chemical 

 irritants contained in the urine. The researches of Krogius, Schnitz- 

 ler, and of Schmidt and Aschoff show that next to the colon ba- 

 cillus the microorganisms most commonly found in cases of cystitis 

 and of pyelonephritis is a proteus (Proteus vulgaris?). 



At the date of the publication of the monograph of Schmidt and 

 Aschoff the Bacillus coli communis had been found in pure culture in 

 sixty cases of cystitis, and the proteus in thirteen cases. 



An important point to be kept in view is the fact that when Ba- 

 cillus coli communis is found in the urine in pure culture, this fluid 

 is more or less acid, as the bacillus in question does not give rise to 

 alkaline fermentation, at least not under the conditions found in the 

 bladder and in the absence of retention. But when proteus is present 

 the urine is almost always ammoniacal. 



DENGUE. 



McLaughlin (1886) has claimed to find micrococci in the blood of patients 

 suffering from dengue. No satisfactory evidence of their etiological relation 

 has been presented, and his observations have not yet been confirmed by 

 other investigators. 



DENTAL CARIES. 



The extended researches of Miller lead him to the conclusion that dental 

 caries is due to various microorganisms described by him. In a paper pub- 

 lished in 1894 his conclusions are formulated as follows : 



"1. In infectious processes in the pulp, almost without exception, we 

 have a mixed infection, and cocci and bacilli are found with about equal fre- 

 quency ; somewhat less frequently, long slender filaments and spiral forms 

 are encountered. At times very peculiar forms are seen ; spore-bearing 

 rods and filaments are occasionally encountered. 



"2. The microscopical examination of cover-glass preparations justifies 

 the view that micrococci are especially concerned in the production of pus. 



"3. The bacteria make their way to the pulp principally through the 

 carious dentine, and a thin layer of hard dentine does not protect it with cer- 

 tainty from infection. Infection of the pulp through the blood-vessels may 

 IM- possible in certain cases, but has not been demonstrated. 



"4. The pulp is predisposed to infection by the action of products formed 

 in the carious dentine (acids-ptomaines). 



"5. In disease of the pulp bacteria are chiefly concerned which cannot 

 be cultivated. 



"(>. Various bacilli which can be cultivated have been found in di- 

 pulp, but for the most part they are non-pathogenic. 



"7. The typical pyogenic cocci, Streptococcus pyogenes aureus and allms, 

 and Streptococcus pyogenes, are seldom found in pus from the pulp, 

 the contrary, various cocci are found, ('specially a group of nearly related 

 snecies, which cause pus-formation in mice. This question has not yet been 

 cleared up. 



