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. 1914 edition. Excerpt: .of the danger of bursting the containers. Planting the Samples.

--If possible, the planting should be accomplished on the spot, on account of the multiplication which is inevitable with delay. If this is not possible, no greater delay should be permitted than is absolutely necessary. For qualitative determinations, two sets of plates should be made: one on regular agar and one on litmus lactose agar. On the second and third days the regular agar plates should be looked over, and any which show bad spreaders or a number of colonies so large that danger of obscuring the count would result if they were incubated longer should be transferred to the refrigerator. On the fourth day all the regular ug.ir plates should be removed and counted. The temperature at which they should be kept is 20 C. The litmus lactose agar plates should be incubated at 40 C.

for 18 to 24 hours only, after which they should be removed for counting.1 When working on a water of unknown character hitherto unexamined, different amounts of the sample--1, 2, 3, and more drops--should be used, since one can have no definite idea of its bacterial richness. 1 Personal communication from Mr. II. W. Clark, chemist in charge of the Lawrence Experiment Station of the Massachusetts State Hoard of Health. In quantitative work, the amounts taken should be measured with the greatest accuracy, especially when preliminary determinations have shown such a number of organisms as to make great dilution with sterile water necessary, for any departure from absolute accuracy introduces an error which will be multiplied according to the degree of dilution. When bulb tubes are used, their contents are exxlled with the aid of gentle heat, which causes the small amount of contained air to expand.