On the cultivation of bacteria / by Edgar M. Crookshank.

  • Edgar Crookshank
Date:
[1886]
Catalogue details

Licence: Public Domain Mark

Credit: On the cultivation of bacteria / by Edgar M. Crookshank. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    can study the relative position of the individual micro-organisms one to another, and in some cases very beautiful preparations result. A perfectly clean cover-glass is carefully deposited on a plate, or potato-cultivation, and gently and evenly pressed down. One edge is then levered up with a needle, and the cover-glass lifted off by means of forceps. The preparation is then allowed to dry, passed three times through the llarne, and stained as already described. In the case of plate-cultivations, especially where no liquefaction has taken place, the growth is bodily transferred to the cover-glass, and a vacant area mapped out on the jelly corre- sponding exactly with the form and size of the cover-glass which was employed. In illustration of this method, I would call attention to a bacillus occasionally present in the air, of which I have been unable to find any written description, and for which I would suggest the name Bacillus figurans. (Plate III. figs. 1 and 2.) In plate-cultivations this bacillus produces a cloudiness which gradually creeps over the surface of the gelatin. If a preparation is made in the manner I have just described, this growth is found to consist of rods which vary considerably in length. These rods lie parallel to one another, and form rows or chains which become twisted at intervals into the most curious convolutions, from which offshoots are continued in various directions. These long shoots or processes become in turn at intervals twisted into varying shapes and figures. If nutrient jelly in a test-tube be inoculated with a platinum needle charged with the bacilli, the growth appears in the form of windings on the free surface which are visible to the naked eye, from these fine filaments spread downwards into the substance of the jelly. Cultivated on a sloping surface of nutrient agar-agar the filaments spread transversely from the central streak, giving a feathery appearance. Cheshire and Clieyne have described a peculiar mode of growth of the Bacillus alvei in plate-cultivations, and Hauser has photo- graphed the peculiar grouping of certain bacteria connected with decomposition. An interesting phenomenon which Hauser has also observed in connection with the last-mentioned bacteria, is the peculiar individual movement which they possess on solid media. This can he most conveniently studied by cultivating the bacilli in a glass capsule. The bacilli often move singly, or meet and progress in pairs, or form chain-like processions; possibly the movements are accounted for by the existence of a film of liquid as they are observed only on solid media containing less than ten per cent, of gelatin. We may also apply the method of plate-cultivation to the examination of water, and to studying the bacteria which exist in [29]