MICROSCOPICAL TECHNIQUE. 211 



rings the edge with a very Httle of the same material, following this 

 with repeated layers of cement (King's preferred). 



Examination of the Blood of Amphibia."^— Herr M. C. Dek- 



huyzen uses test-tubes holding 8 ccm. and having a diameter of 

 14 mm. These are placed in a wooden stand and filled with the 

 fixation fluid or with simple salt solution. In the latter case they 

 are filled first with water and boiled, and the slides are also treated 

 in the same way ; the cover-glasses are cleared with acetic acid and 

 water, and, after drying, with ether. The two fluids used were — 

 (a) [i] A 2 per cent, solution of osmic acid, [2] 6 per cent, acetic 

 acid containing 24 per cent, of a watery solution of methylen- 

 blue, and a little (o"oi4 per cent.) acid fuchsin ; (d) the other 

 fluid contained 20 volumes of acetic acid mixed with 80 volumes 

 of methylen-blue solution, 6 volumes of this fluid mixed with 14 

 volumes of i/sth per cent, solution of acid fuchsin gave the 

 required concentration. 



Before every fixation 2 ccm. of the last deep-blue mixture was 

 well mixed with 6 ccm. of 2 per cent, osmic acid and placed in 

 small tubes, which were filled up to the top. 



It is important to be very careful in allowing the blood when it 

 comes from the blood-vessels to come into the most intimate 

 contact with the fixing mixture. The blood-cells sink to the 

 bottom. After thirty minutes a drop of the fluid should be placed 

 on a slide, and then some of the bottom be drawn up and added 

 to it ; the cover-glass should be run round with xylol balsam. The 

 preparations must be kept from the light. 



Sterilising Incoagulable Alb umen.t—M. E. Marchal suggests 

 that the action of certain salts may be utilised to prevent the 

 coagulation of egg-albumen when heated to 100 deg. These salts 

 are borate of soda, sulphate of iron, and nitrate of urea. The 

 following are the quantities of these substances to be used for the 

 purpose : — Solutions of 2 to 5 percent. : — Borate of soda, '05 grm. 

 per litre ; sulphate of iron, "001 — '006 grm. per litre. Solutions of 



* Journ. R. Mic. Soc, 1893, P- ^l^; from the Verhandl. Anat. Gescll.. 

 1892, pp. 90—93- 



\ Journ. R. Mtcr. Soc, 1893, p. 112 ; from the Bull. Acad. Roy. Set. de 

 Belgique, xxiv. (1892), pp. 323 — 27. 



