On May 27th, 1862, we completely filled a flask, capable of holding 2·780 litres (about five pints), with the solution of lactate and phosphates.[144] We refrained from impregnating it with any germs. The liquid became turbid from a development 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 mercury, 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 accompanying 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 field, apparently making efforts 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.” [Illustration: Fig. 70.] One of the best methods that can be employed for the microscopical 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 wish 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 driven into the bulb _l l_, until it becomes quite full and the liquid flows over into the glass V. In this manner we may bring the vibrios under observation without their coming into contact with the least trace of air, and with as much success as if the bulb, which takes the place of an object glass, had been plunged into the very centre of the flask. The movements and fissiparous multiplication of the vibrios may thus be seen in all their beauty, and it is indeed a most interesting sight. The movements do not immediately cease when the temperature is suddenly lowered, even to a considerable extent, 15° C. (59° F.) for example; they are only slackened. Nevertheless, it is better to observe them at the temperatures most favourable to fermentation, even in the oven where the vessels employed in the experiment are kept at a temperature between 25° C. and 30° C. (77° F. and 86° F.).