298 STUDIES ON FERMENTATION. 



nieut of bacteria, and then underwent butyric fermentation. 

 By June 9th the fermentation had become sufficiently active to 

 enable us to collect in the course of twenty-four hours, over 

 mercur}^ as in all our experiments, about 100 cc. (about 6 cubic 

 inches) of gas. By June 11th, judging from the volume of gas 

 liberated in the course of twenty-four hours, the activity of the 

 fermentation had doubled. We examined a drop of the turbid 

 liquid. Here are the notes accompan3ang the sketch (Fig. 70) 

 as they stand in our note-book : — " A swarm of vibrios, so 

 active in their movements that the eye has great difficulty in 

 following them. They may be seen in pairs throughout the 



Fig. to. 



field, apparently making elibrts to separate from each other. 

 The connection would seem to be by some invisible, gelatinous 

 thread, which yields so far to their efforts that they succeed in 

 breaking away from actual contact, but yet are, for a while, so 

 far restrained that the movements of one have a visible effect 

 on those of the other. By and by, however, we see a complete 

 separation effected, and each moves on its separate way with 

 an activity still greater than it had before." 



One of the best methods that can be employed for the micro- 

 scopical examination of these vibrios, quite out of contact with 

 air, is the following : — After butyric fermentation has been 

 going on for several days in a flask, A (Fig. 71), we connect 

 this flask by an india-rubber tube with one of the flattened 

 bulbs previously described, page 156 (Fig. 31), which we then 

 place on the stage of the microscope (Fig. 71). When we wash 

 to make an observation we close, under the mercury, at the 

 point b, the end of the drawn-out and bent delivery-tube. 

 The continued evolution of gas soon exerts such a pressure 

 within the flask, that when we open the tap r, the liquid is 



i 



