UDDER-PYOBACILLOSIS 



73 



O 



Fig. 20. — Deep colonies of pyogenes 

 bacilli. Serum-gelatin-agar plates. T. 

 38°, 2 days (X30). 



As a rule one searches vainly for surface colonies and 



if he finds one it is extremely thin and consists of a scarcely 



visible whitish-gray round layer about 2 mm. in diameter. 

 In stab cultures in gelatin- agar and agar at 38° C. the 



bacillus pyogenes produces a growth in the line of the stab 



after two to five days which re- 

 sembles a thread. Usually no 



growth occm*s on the surface, but 



when present appears as a fine 



gray point over the opening in 



the stab puncture (Fig. 21 ) . In 



gelatin stab cultures the growth 



is slow and scanty. It also forms 



a thread-like growth along the 



line of puncture in the media 



which shows infundibuhform liquefaction along the stab 



after a week, following which the bacteria form a small 



deposit on the bottom made by the firm media (Fig. 22). 

 On streak cultures on coagulated serum at 38° C. it 

 forms a fine scarcely visible gray thread 

 along the streak in about four days. After 

 six days on the media liquefaction occurs 

 forming a moist glistening groove along 

 the streak. 



In bouillon the bacillus grows in from 

 two to four days at 38° C. without turbid- 

 ity of the media, but shows small fine gray 

 granules which sink to the bottom of the 

 tube, forming a granular deposit. Upon 

 shaking the tube these deposits cause the 



media to become diffusely turbid. 



The bacillus pyogenes coagulates milk at 38° C. in two 



to three days and the coagulum thus formed later liquefies 



with the formation of whey. 



Fig. 21. 



Fig. 22. 



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Fig. 21.— Stab cul- 

 ture of pyogenes bacilli 

 in serum-gelatin-agar. 

 T. 38° C, 4 davs. 



Fig. 22.— Stab cul- 

 ture of pyogenes bacilli 

 in gelatin. T. 20° C, 

 12 days. 



