UDDER-COLIBACILLOSIS 



65 



a Fia. 17. 

 I 



Fla. 18. 



\J 



u 



a nail culture. The nail is wedge-shaped, most vigorous 

 above and often has a fine felt-like contour following the 

 formation of daughter colonies in the media by outwander- 

 ing bacilli (Fig. 18). In soft media like gelatin-agar the 

 nail-like growth is often surrounded by a whitish-gray 

 more or less thick cylindrical zone (wander zone), and the 

 nail-shaped growth in the track of the stab, the stab growth, 

 can become indistinct by a vigorous outwandering of bacilli. 

 The nail head is made of a grayish-white somewhat thin 

 surface membrane which at 38° C. completely covers the 

 surface and in gelatin at 20° C. is small and only covers 

 part of the surface. Gelatin is 

 not liquefied. 



In streaks upon agar at 38° C. 

 it forms whitish-gray round colo- 

 nies, which coalesce and produce a 

 gray band along the streak. In 

 bouillon and peptone water at 

 38° C. the colon bacillus grows 

 with diffuse turbidity of the cul- 

 ture media and formation of 

 distinct bacterial deposits on the 

 bottom of the test tube. As a rule it does not form a 

 membrane on the surface, and if it does it is very thin and 

 small. 



The colon bacillus coagulates milk somewhat quickly, 

 usually in one day, at 38° C, with the production of gas. 



It splits the sugar, glucose, maltose, lactose, and often 

 saccharose with formation of gas and acid so that the 

 medium finally contains 2 to 3 per cent, normal acid. The 

 splitting of saccharose is slow and does not occur at all with 

 some colon bacilli. 



The colon bacillus produces more or less indol in pep- 

 tone water (peptone Witte 3 per cent., sodium chloride 

 0.5 per cent.) in about six days at 38° C. 



5 



Fig. 17. — Cultures of colon bacilli. 

 Stab in serum-gelatin-agar. T. 38° C, 

 3 days. Twodifferent strains, a. with- 

 out and 6. with "wander zone." 



Fio. 18. — Culture of colon bacilli. 

 Stab in gelatin. T. 20° C, 6 days. 

 With downy hair-like peripheral 

 outgrowth. 



