ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 252 



consisted of 3 or 9 vols, of 2 p.c. osmic acid and 1 vol. of 6 p.c. acetic 

 acid and 0*125 p.c. methylen-blue. A trace of acid fuchsin imparted 

 some advantage, but it was not indispensable. Tbe 9/1 osmacet cooled 

 witb ice is suitable for tbe demonstration of thrombocytes or blood- 

 plates in mammalian blood. Tbe finger, or ear of rabbit, is pricked 

 tbrougb the cold osmacet. 



F. Kopscb,* who confirms Deetjen's observations, recommends, as 

 well as tbe other fixatives previously alluded to, 1-2 p.c. osmic acid, or 

 iodopotassic iodide solution. 



P. Argutinsky f points out that it is advantageous to use the 

 Romanowsky-Nocht stain for malaria, as it is excellent for chromatin 

 staining in blood preparations. The films should be fixed in sublimate 

 alcohol, and then stained with the eosin- soda-methylen-blue solution, 

 which gives good pictures of the blood-plates (thrombocytes). 



Method of Making Microscopical Preparations for Photographic 

 Purposes.:}: — G. von Wendt communicates the following procedure for 

 making preparations suitable for photomicrography : — (1) Fixation and 

 hardening. The material is cut up into blocks not exceeding 3 mm. 

 thick, and fixed in 3 p.c. nitric acid for 12-20 hours. Nitric acid-alcohol 

 and picric acid are also good fixatives. From the fixative the blocks 

 are transferred to 90 p.c. alcohol for at least 24 hours. (2) Before 

 the blocks are treated with the first mordant they are immersed in 

 ammonia 1 part and 75 p.c. alcohol 10 parts for 6-10 hours at a 

 temperature not exceeding 15° C, and afterwards in 90 p.c. alcohol 

 for about 24 hours. From this they are transferred for 4-6 hours 

 to a mixture of 75 p.c. alcohol 12 parts, hydrochloric acid 1 part, and 

 then again to 90 p.c. alcohol for 24 hours, after which to water for 

 some hours. (3) Mordant A. As mordants, are used 5 p.c. tungstate 

 of ammonium or ammonium molybdate solution. The process lasts 

 about 24 hours, and the temperature should at first be 17°-20° C, 

 but during the last few hours should not exceed 12°-15° C. After 

 this mordanting the preparations are washed in cold water, and then 

 immersed in 90 p.c. alcohol. (4) The blocks are imbedded in paraffin 

 in the usual way. (5) The sections must be smoothed out over warm 

 alcohol and stuck on with Mayer's albumen-glycerin, and then passed 

 through xylol to water in the usual way. (6) Mordant B. After the 

 water has been run off from the slide, the section is flooded with 2 p.c. 

 iron-alum solution. The slide is then placed in a thermostat at 55° for 

 2-7 minutes. The mordant is then washed off with cold water. (7) 

 Staining. The stain is made from a saturated alcoholic solution of 

 hematoxylin by dropping this into distilled water until the mixture is 

 of a yellowish-brown hue. This staining fluid must stand for some 

 time before it can be employed with advantage. It is used by flooding 

 the section, and then incubating the preparation for 10 minutes at 55°. 

 (8) Differentiation. The stained preparations are differentiated in cold 

 iron-alum solution. (9) After which they are washed in water and 

 mounted in balsam in the usual way. 



* Tom. cit., pp. 541-51. See Zeitschr. wiss. Mikr., xviii. (1902) p. 541. 

 t Tom. cit., pp. 552-4. See Zeitschr. wiss. Mikr., xviii. (1902) p. 342. 

 X Zeitschr. wiss. Mikr., xviii. (1902) pp. 293-5. 



