The Bacterial Soft Rots of Certain Vegetables (Paperback)

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1910 edition. Excerpt: ...had simply been passed through filter paper.' This filter re 'Some students of cytolytic enzyms have objected to the use of filter paper because of the possible action of the enzym upon it. This occurred to us early in our work but repeated observations have shown this enzym is entirely inactive on the celluloses proper. We have, therefore, used Schleicher & Schull's filter paper, both for filtering the broths and for collecting the precipitate. moves the coarser deposits but not the bodies of the bacteria. To the filtrate was then added enough 95% alcohol to render it alcoholic to the desired degree, usually 80%, the precipitate allowed to settle, the supernatant alcohol siphoned off, the precipitate, collected on filter paper, washed with either 95% or absolute alcohol and quickly dried, partially in a current of warm air, then in a desiccator over sulphuric acid. The dried precipitate, which is gray and somewhat brittle, was then powdered before redissolving in water. It is of course important to secure quick drying to avoid the possibility of alteration as a result of bacterial growth or of chemical changes in the precipitate. The drying must also be done at so low a temperature as to preclude danger of injury from heat to the sensitive enzym. In our earlier work we washed out the 35% alcohol with absolute alcohol in order to hasten the drying. Later it was found this made scarcely any difference in the time and no difference in the result, providing the moist precipitate was properly broken up so as to dry out quickly. Spieckermann ( 1902: 165) used absolute alcohol followed by ether, presumably to secure quick drying. Most of our work had been completed before his paper reached us, but we thereupon tested this...