144 BACTERIOLOGY OF THE EYE 



can be seen in the colonies. They have no great tendency to coalesce. 

 According to Zur Nedden, they are not so sharply bordered as are the 

 influenza colonies, and more rapidly become lost to sight on the 

 medium. When isolated colonies occur, especially if such be near to 

 any of the other organisms we have mentioned, their contour may be 

 slightly wavy and their * appearance more opaque and granular ; a 

 yellowish colour may sometimes be noticed. 



In serum bouillon, and also blood bouillon, a faint diffuse cloudiness 

 occurs, which later sinks as a deposit to the bottom of the tube. 



Morphology. The bacilli in cultures, as in the secretion, appear to 

 be very slender and of varying length. Long filaments are often 

 seen, sometimes long, coiled, involution forms, of somewhat greater 

 thickness. 



Morax recorded these ; Hofmann found them very plentifully in old 

 colonies ; Weichselbaum, Miiller, and Kamen also describe them ; and 

 I have often seen them myself. The ends of the long forms are some- 

 times slightly thickened ; these, however, should not be confused with 

 the xeroso bacilli, which are much thicker, and besides, are stained 

 positively by Gram (see Figs. 15, 16, 17). 



The bacilli are non - motile ; they decolorize rapidly with Gram ; 

 they are aerobic. 



Resistance of Cultures. The bacilli rapidly die in cultures ; after 

 five days, and often much less, they can no longer be propagated. 

 Growth ceases at 20 C., but, if kept moist, they remain alive for sixty 

 hours. After heating for ten minutes to 50 C., some of the bacilli still 

 remain alive, but they can only withstand a temperature of 60 C. for 

 one to two minutes. "Weichselbaum and Miiller found their cultures 

 dead after fifteen minutes at 60 C. 



Hofmann satisfied himself that the bacilli were not killed by an 

 hour and a half at 70 C. He considered it possible that, under favour- 

 able circumstances, the organisms could remain alive for a longer 

 time outside the body. In liquid human serum at brood temperatures 

 they live for six days. 



Half an hour's exposure to the sun's rays did not kill the bacilli in 

 culture when kept at 43 C., but after two and a half hours they were 

 no longer alive. 



Contagion. Prophylaxis. 



Wilbrand, Saenger, and Staehlin considered that transference by the 

 air must be presumed to explain the extraordinarily rapid spread of 

 the epidemic which they studied. 



