ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 383 



with the lardaceous change can be obtained by merely drying. The 

 preparations are stained with methyl-violet, differentiated with very 

 dilute acetic acid, washed in water and dried in the air. They are then 

 cleared up in xylol, and mounted in balsam. This method, which, of 

 course, is only applicable to paraffin sections, does not succeed with iodine. 



(6) Miscellaneous. 



New Method of enumerating Leucocytes.* — W. B. Leishman, at 

 a meeting of the Pathological Society of London, held March 20, 1906, 

 described a method of enumerating leucocytes, by which it was possible 

 to dispense with the use of expensive apparatus, of a special diluting 

 fluid, and of a mechanical stage. Two pipettes are required, one an 

 ordinary 1 c.cm. pipette graduated to 0*01 of a c.cm., and the other a 

 capillary pipette to deliver 5 c.cm. Five (5) c.cm. of the blood to be 

 treated is taken into the capillary pipette and at once diluted 200 times 

 by being blown into 095 c.cm. of water, previously measured by the 

 larger pipette. The mixture is well stirred and shaken, and two succes- 

 sive volumes of 5 c.cm. are taken and discharged side by side on a slide. 

 The drops are allowed to dry, and then stained with Leishman's stain. 

 The whole number of the leucocytes are then counted by the aid of a 

 ruled cover-glass in the following way : — A drop of Leishman's stain is 

 allowed to evaporate on the surface of a cover-glass ; a thin film is left, 

 insoluble in water or cedar-oil, in which is ruled a series of parallel lines, 

 with the point of a needle. A drop of cedar-oil is then placed on the 

 film, and on it is dropped the cover-glass, ruled surface downwards. 

 Both drops are then counted. In this way the whole of the leucocytes 

 in 10 c.cm. of the diluted blood are enumerated, and the number in 

 1 c.cm. of blood is obtained by multiplying the result by 20. In dealing 

 with leukhsemic, or with leucopenic blood, the dilution is readily altered 

 to facilitate counting. As compared with Grower's hgemocytometer, the 

 readings by the author's method underestimates by about 5 p.c. 



Bohm, A. A., & Davidofp, M. — Textbook of Histology, including microscopical 

 Technics. Translated by H. A. Cushing. 



Philadelphia : 2nd revised and enlarged edition, 1904, 8vo. 



528 pp., and plates. 



Hall, Walker J., & G. Heexheimes — Methods of Morbid Histology and 

 Clinical Pathology. 



London and Edinburgh : Green and Sons (1906) 8vo, xvi. and 290 pp. 



Mollek, J. — Mikroskopie der Nahrungo-ond Genuszmittel aus dem Pflanzenreich. 



Berlin : Jul. Springer (1905) xvi. and 599 pp., 599 figs. ; 



2nd edition, revised and enlarged with the 



collaboration of A. L. Winton. 



Senpt, E. — Mikroskopische Untersuchung des Wassers mit bezng auf die in 



Abwassern and Schmatzwassern vorkommenden Mikro-organismen nnd Verun- 



reinigungen. Wien : Jos. Safar (19G5) 196 pp., 180 figs, in text 



and 10 plates. 



* Brit. Med. Journ., (1905) i. p. 680. 



