Biological Examination of Drinking-Water.
—Migula (Centralblatt für Bakteriologie und Parasitenkunde) has come to the conclusion that the number of colonies that are developed in plate cultures, is not an index of the potability of waters examined by this method. He finds, however, that there is a relation in the number of species found in water and its purity. If a large number of varieties are present it speaks generally for the unhealthfulness of the water. We must refer the reader for fuller particulars to the original and the tables which accompany it, representing as they do, over 400 examinations.He closes with the following conclusions: first, that the number of colonies developed by 1 ccm. furnishes no ground for concluding as to the potability of such waters; second, the bacteria of decomposition are absent from running water; third, the bacteria of decomposition are most numerous in water containing 1,000 to