ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 97 



to sediment. Pus, urine, and other secretions may be treated in the 

 same way. 



Method for Examining quickly moving 1 Micro-organisms.* — Herr 

 H. Plenge gives the following procedure for obtaining an extremely thin 

 layer of fluid in which the motility of micro-organisms is impeded. A 

 very thin cover-glass which has been kept for some days in absolute 

 alcohol is carefully dried. A trace of pure glycerin is then rubbed on 

 with the finger tip, and afterwards rubbed off with a clean clotb. In 

 this way an extremely thin and regular layer can be obtained from a 

 culture fluid after the superfluous fluid is poured off. 



Method of Measuring the Bactericidal Power of the Blood, t — 

 Prof. A. E. Wright has devised a method of determining in a quanti- 

 tative manner the bactericidal power of the blood. Measured volumes 

 of serum and of graduated dilutions of serum are introduced into a series 

 of capillary cultivation tubes along with a series of equal volumes of a 

 gelatin culture containing an appropriate number of bacteria. Mixture 

 of the contents of the serum and culture is then effected in the capillary 

 tube. It will be noticed that by this arrangement the serum comes in 

 contact with the bacteria only after they have been suspended in a fluid 

 which is sufficiently viscid to make it impossible for them to come 

 together into groups. After the gelatin has solidified, the tubes are 

 incubated for a period of two or more days. The number of colonies 

 is then counted under the Microscope, and the results compared with 

 those from a series of control tubes filled with an equal volume of the 

 gelatin diluted with an indifferent diluting fluid. For the details of the 

 procedure, which are given with much minuteness, the original should 

 be consulted. 



Microscopy of Starches.! — Dr. H. Gait has collected together in a 

 booklet the results of his observations on some of the more commonly 

 occurring starches, and has illustrated his work with 22 original photo- 

 micrographs. The author prefers to use the term microphotograph on 

 the ground of euphony, but does not suggest that this atavistic spelling 

 is easier to write or print. Another example of an old and not to be 

 admired custom is the different magnifications under which the starches 

 have been photographed. For the purpose of comparison and for the 

 use of students it is wiser to adopt a single standard, as was done by 

 W. Griffiths in The principal Starches used as Food (1892). Indeed, 

 Griffiths' work is superior in every way, not only in the photomicro- 

 graphs but also in the letter-press, which contains a large amount of 

 useful information. 



Simple Method for Estimating the Damage to Living Cells.§— 

 Dr. M. Neisser states that the reducing power of living cells such as 

 leucocytes may be used as an estimate of their vitality. Thus the normal 

 leucocyte speedily decolorises methylen-blue ; but if in any way damaged, 

 the cell is unable to exert this power, and the solution retains its hue in 

 proportion to the vital activity of the cell. If 0-5 ccm. of aleuron- 



* Verhandl. Naturhist.-med. Vereins zu Heidelberg, vii. p. 218. See Zeitschr. f. 

 angew. Mikr., vi. (1900) p. 188. t Lancet, 1900, ii. pp. 1556-61 (4 figs.). 



% Bailliere, Tindal, and Cox, London, 1900, 108 pp., 22 pis. 

 § Miinchener med. Wochenschr., xlvii. (1900) pp. 1261-2. 



Feb. 20th, 1901 H 



