CHAPTER XXIV. 

 SPIRZLLACE^E AND THE DISEASES CAUSED BY THEM. 



Spirillum Rubrum. Esmarch discovered this organism in 

 the body of a dead mouse. It is of chief interest as a harmless 

 example of spiral bacterium for class study. It grows rather 

 slowly at room temperature without liquefying gelatin. A dull 

 red pigment, insoluble in water, is produced even in the absence 

 of oxygen. Growth occurs at 37 and also in the refrigerator at 

 5 to 10 C. When grown at temperatures above 20 C. the 

 organism is a relatively short, slightly bent rod and its spiral 

 nature is not very evident. At 10 C. beautiful long spirals are 

 produced in broth cultures. It is actively motile. 



Spirillum Cholerae (Microspira Comma). Koch in 1883 

 discovered this organism in the intestinal discharges of patients 

 suffering from Asiatic cholera, and continuing his studies in India 

 in the same year established this organism as the probable cause 

 of cholera. It occurs in the intestinal contents and feces of cholera 

 patients, often in great abundance, rarely in the feces of healthy 

 persons, and has been found at times in surface waters, and in 

 drinking water during epidemics of cholera. 



Sp. cholera is a curved cylinder about 0.4 /x in thickness and 

 i.5/z in length. In older cultures in broth long spiral forms occur. 

 There is considerable variation in shape in cultures older than 

 48 h,ours. The organism is actively motile and possesses a single 

 flagellum at one end. Those short spirals showing more than 

 one flagellum are not to be regarded as true cholera germs. 

 Spores have not been observed. The spirillum stains readily 

 and is Gram-negative. 



It grows well and rapidly on ordinary media. The reaction 

 needs to be distinctly alkaline to litmus as the organism is very 



345 



