were found to have come to a state of rest. In order still further to test these views, I took an infusion of turnip, containing a multitude of _Bacteria_ whose movements were of the languid description, and divided it into two portions. One of these portions was boiled for about a minute, whilst the other was not interfered with. Then, after the boiled solution had been cooled, a drop was taken from each and placed at some little distance from one another on the same glass slip; covering-glasses half an inch in diameter were laid on, and the superfluous fluid beneath each was removed by a piece of blotting-paper. When only the thinnest film of fluid was left, the covering-glasses were surrounded by a thick, quickly-drying cement.[28] Examined with the microscope immediately afterwards, it was generally found that the _Bacteria_ which had been boiled presented a shrunken and shrivelled aspect--whilst some of them were more or less disintegrated--though, as far as movement was concerned, there was little to distinguish that which they manifested, from that of their plumper-looking relatives which had not been boiled. [28] I always employ a solution of gum mastic and bismuth in chloroform. If a different varnish be employed, it is of course necessary to ascertain whether its application is injurious to the enclosed _Bacteria_. If the specimens were examined again after twenty-four or more hours, there was still very little difference perceptible between them, as regards their movements. And the same was the case when the specimens were examined after a lapse of some days or weeks. One important difference does, however, soon become obvious. The _Bacteria_ which have not been boiled, undergo a most unmistakeable increase within their imprisoned habitat; whilst those which have been boiled, do not increase. The two films may be almost colourless at first (if the _Bacteria_ are not very abundant), but after a few days, that composed of unboiled fluid begins to show an obvious and increasing cloudiness, which is never manifested by the other. Microscopical examination shows that this cloudiness is due to a proportionate increase in the number of _Bacteria_.