March 31, 1905.] 



SCIENCE. 



497 



similarly to, and as a substitute for, the 

 glass top, except that it is best not to wash 

 it between uses. 



Its function is to absorb the excess mois- 

 ture which, when glass tops are used, re- 

 suits in 'spreaders.' 



In use, the percentage of 'spread' plates 

 found in routine plating work of milk on 

 agar at 37° C. in a saturated atmosphere 

 has been reduced from 38 per cent, with 

 glass tops (plates inverted) to 3 per cent, 

 with porous tops (plates not inverted). 



{Journal of Medical Research, 1904, 

 XIII., 93.) 



Staining Bacterial Fields under Micro- 

 scopic Observation. — This is a mechanical 

 device for applying stains, decolorizers, 

 moi'dants, etc., directly and readily to the 

 lower smeared surface of a cover-slip, in 

 such a manner as to stain, decolorize or 

 mordant, successively, in any order, a 

 selected microscopic field, while the same 

 is under observation, with provision also 

 for a water flush to remove the surplus 

 solutions applied. Particularly useful for 

 Gram's stain, comparison of different 

 stains, etc. 



Method for Obtaining Smears for 

 Flagella Staining. — The organism to be 

 obtained is grown in broth, on the principle 

 that in broth flagella are better developed 

 than on the solid media usually recom- 

 mended. To remove the broth from the 

 organisms, repeated centrifugalization, de- 

 cantation and addition of distilled water 

 or normal salt solution is used. Numerous 

 experiments show that the centrifugaliza- 

 tion does not denude the bacilli of flagella 

 to any extent. 



{Journal of Medical Research, 1904, 

 XIII., 97.) 



A Method of Obtaining a High Percentage 

 of Serum from Blood: C. W. Lincoln, 

 Glenolden, Pa. 



In this method the blood is di-awn into 



a tall narrow bottle without shoulders. A 

 drip flask is made of a narrow glass per- 

 eolater of the same caliber as the blood 

 bottle, resting on a wide mouth quart 

 bottle, the two being bound together by a 

 broad band of paper tied firmly to each. 

 Into the bottom of the percolator is 

 dropped an inverted cone of coiled 

 nickeled wire, the upturned base of which 

 shows a flat surface of coiled wire with 

 intei-spaces of not over one fourth of an 

 inch. A paper cap is put on the perco- 

 lator and the whole sterilized together. 

 When clotting has taken place and all the 

 serum has been drawn or poured off, the 

 clot is gently slid from the blood bottle 

 into the drip flask, both being held nearly 

 liorizontally. The two vessels being of the 

 same caliber, the clot is but slightly injured 

 and rests on the wire cone on its tough 

 buffy coat, so that the serum that drips is 

 not at all reddened after the drip flask has 

 stood in a refrigei-ator for 24 hours. By 

 this method 46 per cent, of serum may be 

 obtained and if the pouring is done in a 

 comparatively dust-free room no contami- 

 nation occurs. 



Note on iltc Occurrence in the Natural 

 Waters of Eastern Massachusetts of Bac- 

 teria Simidating Sewage Forms: E. G. 

 Smith, IMassachusetts Institute of Tech- 

 nology. 



The author has observed in studying the 

 bacteria of natural waters that species oc- 

 cur with considerable frequency which ex- 

 hibit to a marked degree the reactions of 

 colon bacilli, and he points out that these 

 organisms may sometimes lead to erroneous 

 conclusions as to the sanitary quality of a 

 water. 



Examination of 100 samples of water 

 taken from sources 'presumably polluted.' 

 The samples are from springs and brooks, 

 public water supplies, pools and other 

 sources where rapid personal inspection of 



