ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 537 



The box, made of paper in the usual way and one-fourth filled 

 with the imbedding mass, is kept in the bath until the mass is har- 

 dened enough to support the brain. The brain is next placed on the 

 hardened stratum and covered with the fresh mass. The second 

 stratum is hardened just enough to hold the brain in place, and then 

 a third is added, filling the box. 



The whole mass must now be allowed to harden through and 

 through, requiring about fifteen minutes. The hardening is completed 

 by passing the box through three grades of alcohol — 80, 90, and 100 

 per cent., allowing it to remain twenty-four hours in each. When 

 the mass becomes nearly white and ceases to discolour the alcohol it 

 is ready for cutting. 



Method of preparing permanent specimens of Stained Human 

 Blood. — Dr. V. D. Harris writes us as follows : — 



Although at first sight a very simple matter, it is found in prac- 

 tice to be anything but easy to prepare specimens of human blood, so 

 that the corpuscles may retain their shape and may be at the same 

 time well stained. After the trial of a large number of different 

 methods I recommend the following as giving the most satisfactory 

 results. The finger is pricked and a large drop of blood is allowed to 

 exude ; a perfectly clean cover-glass is lightly drawn upon the top of 

 the drop so that a very thin layer of blood adheres, so thin as hardly 

 to be evident until it is dry. It is then dried in the air or put at 

 once without drying into one of the following solutions, viz. chromic 

 acid l/l'i per cent. ; bichromate of potassium 1/2 per cent. ; methy- 

 lated spirit or absolute alcohol for five or ten minutes, washed 

 in water and again dried. The specimen is now ready for stain 

 ing. The best dye for this purpose will be found a recently 

 prepared 1 per cent, solution of Spiller's purple in water to 

 which a few drops of alcohol have been added, or a weak 

 spirit solution of rosein. A few drops of one or other dye 

 having been filtered into a watch-glass, the cover-glass is placed upon 

 the surface of the solution blood downwards, f nd allowed to remain 

 so for from five to ten minutes. It is then removed, washed for some 

 time in a gentle stream of distilled water, dried thoroughly, and 

 mounted in Canada balsam with or without previous treatment in 

 clove oil for a minute or two. On examination of the specimen the 

 coloured corpuscles should be found of normal shape and coloured 

 purple or red, according to the dye used, and the colourless corpuscles 

 similarly stained. The method with Spiller's purple will be found 

 especially useful when blood is examined in disease conditions in 

 which the existence of micro-organisms is suspected, and is superior 

 to any other of the many anilin dyes (such as methyl-violet) which 

 I have tried. 



Demonstrating the Origin of Red Blood-corpuscles in Cartilage 

 at the Margin of Ossification.* — Dr. B. Bayerl, after decalcifying 

 and hardening the specimen in alcohol, imbedding it in paraffin, 

 and cutting, treats the sections with turpentine, soaks in absolute 



* Arch. f. Mikr. Anat,, xxiii. (1884) pp. 30-45. 



