ACTINCfMYCETES. 381 



presents difficulties for the following reasons: 'All the 

 mycelia seen by microscopic examination are not living ; 

 as a rule, they grow slowly even under the best of cir- 

 cumstances ; and generally there are many other, more 

 rapidly growing, living organisms in the pus. When 

 pure cultures are obtained, it grows (according to Bos- 

 trom) on all the ordinary artificial media. It develops 

 at room-temperature, but better at that of the body. 



It grows both with and without oxygen. 



The young colonies appear as grayish points com- 

 posed of a felt-work of fine threads. As the colonies 

 become older they become denser and more opaque. 

 Very old colonies are almost leathery in consistency. 

 On blood-serum the growth after a time assumes a 

 salmon, an orange, or a yellowish-red color. Growth 

 on gelatin is accompanied by slow liquefaction. 



A yellowish-red growth, limited in extent, occurs on 

 potato. It causes no clouding of bouillon, but grows as 

 cottony clumps that sink to the bottom. 



The bulbous extremities seen upon the mycelial 

 threads fresh from the pus are not usually seen under 

 conditions of artificial cultivation. They are sometimes 

 observed in colonies located in the depths of solid media. 

 The white, powdery coating seen on old colonies repre- 

 sents the so-called i( spores." They are not, however, 

 resistant to heat, being destroyed, according to Domec, 

 by 75 C. in five minutes. 



Bovines are the animals most frequently affected. 

 The disease has been seen in swine, dogs, and horses. 



The most common seat of the disease is the jaw, and 

 this, together with the fact that particles of fodder, such 

 as bits of grain, chaff, straw, and barley beard, have 

 been detected in the diseased tissues in association with 



