EXPERIMENT STATION BULLETINS 



253 





■ii 



mmJ¥m 



"-ts 



.v-i. 



2-f. 







^.M 





m 



«.^ 



Fig. 4. 



-■S-^iV. 



Gelatin and agar tube cultureo or ropy 

 cream bacillus. 



continuous growth appears, but it 

 is confined to the puncture. On 

 the surface, a moist glistening 

 white mass is seen about the point 

 where the needle entered the gela- 

 tin. The borders are somewhat 

 irregular. The extent of the growth 

 is limited to a very small surface 

 and resembles a large colony which 

 is not inclined to spread. In hold- 

 ing it to the light, an iridescent 

 hue is revealed. 



Agar Streak Culture: Along 

 the entire streak and extending 

 ^ but a very short distance' from the 

 streak, is a whitish slimy and 

 glistening growth with a scalloped 

 border. The development is very 

 rapid. 



Potato Streak Culture: On the 

 surface of the potato, it produces 

 a yellowish white, creamy growth 

 which rises above the surface and 

 is confined to that portion inocu- 

 lated, with no tendency to spread. 



Bouillon Culture: At first the 

 bouillon becomes cloudy and event- 

 ually a scum forms over the top. 

 When the needle is applied to this 

 it is possible to draw out a string 

 several feet long and so fine that it 

 is virtually invisible. As the cult- 

 ure becomes older, these bacteria 

 form a jelly like mass in the 

 bouillon and the bouillon itself 

 responds as jelly. It is a difficult 

 task to break up this mass by the 

 addition of more liquid. . 



Milk Culture: When bacteria 

 produce any peculiar condition of 

 the milk, as the formation of lactic acid, butyric acid and other products, 

 the investigator attempts to determine that constituent of the milk from 

 which any one of these products is formed. In the lactic acid fermenta- 

 tion, the sugar of milk will gradually disappear until a certain per cent of 

 acid is formed. Inasmuch as stringy milk may be produced from the 

 sugar of milk or some of the protied substances, as caseine, it therefore 

 become3 an interesting feature of the life history of this class of micro- 

 organisms to study their action upon the various component parts of milk. 

 Although the cultured properties of the bacillus in question indicate 

 whence comes this ropiness and preclude any further analysis, to settle 

 the matter definitely an estimation was made of some of the substances 

 constituting milk. This was carried out as follows: Flasks of milk were 

 sterilized after the usual method, and were inoculated with the bacillus. 



