TEXT-BOOK OF BACTERIOLOGY. 341 



able to cultivate artificially outside of the body and the pathogenic 

 properties of which he ascertained by experiments on mice and 

 rabbits. His observations were fully confirmed by Lydtin and 

 Schottelius and particularly by Schiitz. They also produced typi- 

 cal erysipelas from cultures by a successful transmission to hogs. 

 It is, therefore, no longer doubted that this special kind of bacterium 

 is the cause of the hog erysipelas. 



They are very small, slender rods, looking like delicate bristles 

 or tiny needle-shaped crystals. Though usually single or in pairs, 

 they sometimes form long threads, and may interlace into a pretty 

 network. They have the power of voluntary motion; it is as yet 

 unknown whether they form spores. They grow at either room or 

 breeding temperature, belong to the semi-anaerobic kinds, thrive 

 rather better in the absence of oxygen, stain with the usual anilin 

 colors, and can be excellently prepared by Gram's method. 



On the gelatin plate there appears, on the second or third day, 

 at the bottom of the medium a peculiar cloudiness of grayish- blue 

 or silver-gray color, distinctly perceptible only on a dark back- 

 ground. Wherever the colonies have grown to a certain extent, 

 extremely delicate, greatly ramified, and mistily transparent masses 

 are recognized with the naked eye; on the whole, they resemble 

 somewhat the appearance of a " bone corpuscle " with its tiny proc- 

 esses and shoots. The colonies grow on, coalesce, and impart to the 

 entire plate a dim, grayish glimmer. They do not, as a rule, ad- 

 vance to the surface of the medium. The gelatin is not liquefied. 

 Microscopic examination adds nothing, and is of little avail on ac- 

 count of the extraordinary fineness and transparency of the colonies. 



Test-tube culture shows, in the neighborhood of the inoculation 

 puncture, dense masses of the appearance noticed in the colony on 

 the plate. Development usually commences but a short distance 

 below the free surface of the gelatin and becomes strongest in the 

 deeper layers. It increases but slowly and gradually, until, finall} 7 , 

 the entire gelatin appears traversed by dim, gray clouds. A very 

 slight softening of the gelatin is noticed in the course of several 

 weeks which is followed (in consequence of evaporation and simul- 

 taneous drying) by the formation of a funnel. 



On agar and blood-serum (especially at breeding temperatures) 

 a very delicate, hardly perceptible coating is formed along the 

 inoculating line. No development takes place on potatoes. 



Experiments of transmission of such cultures proved that hogs, 

 pigeons, rabbits, domestic and white mice were accessible to infec- 

 tion produced in the body-cavities by inoculation, subcutaneous ap- 

 plication, and injection, while Guinea-pigs and (strange enough) 



