854 SUMMARY OF CURRENT RESEARCHES RELATING TO 



this purpose wax is lueltod and poured out on a piece of plate glass, 

 nud this sheet of wax is rolled level with au iron roller. The wax 

 Bliccts may bo simple, or laid on paper which has been previously 

 saturated with wax, and the roller used may bo hot or cold according 

 as the wax is softer or harder. Instead of glass a lithographic stono is 

 recommended. 



Making Mounts Photographic.*— Mr. G. W. Eafter writes that 

 there is a phase of mounting which could well bo impressed upon the 

 attention of microscopists. That is, to make all mounts with reference 

 not merely to use under the tube, but with reference to good photographic 

 results. lie thinks he is justified by experience and study in saying 

 what has been well said before, that whatever can be seen with an 

 objective and eye-pieco can be photographed as clearly as it can bo 

 seen, provided proper methods of preparation for photography are 

 followed. Ho thinks it may bo further stated that such methods of 

 preparation will not diminish their value under the tube. " Go through 

 a cabinet of ordinary mounts and see how few arc jihotograiihable ! The 

 enormity of the thing appears when wo consider that nearly all classes 

 of mounts, including opaque, may be readily photogi-aphed if properly 

 prepared. To this, however, there are a few exceptions. The additions 

 to general knowledge of matters microscoi^ic which could be mado, if 

 all working microscopists would prepare with reference to photography 

 is simply enormous." 



Improved method for Enumerating Blood-corpuscles.f — M. Mayct 

 has made a further improvement in artificial serum used in the enumera- 

 tion of blood-corpuscles. Blood to the volume of 4 mm. is first mixed 

 with 500 mm. of a watery 1 per cent, solution of osmic acid by which 

 the corpuscles are fixed and rendered colourable. At the end of three 

 minutes 500 mm. of the following liquid is added : — Glycerin, 45 ccm. ; 

 distilled water, 55 ccm. ; eosin in aqueous 1 j^er cent, solution, 17 ccm. 

 The red corpuscles are brightly stained, the leucocytes being scarcely or 

 not at all coloured, and this difference of tint allows the two kinds of 

 corpuscles to be easily counted. The distribution of the corpuscles on 

 the side is quite uniform, owing to the fact that the mean density of the 

 two fluids used for dilution is equal to about 1084, and also to the 

 viscosity of the glycerin. The further steps in the procedure are as 

 heretofore. 



Improved method for the Bacteriological Examination of Air.| — 

 The method adopted by MM. Straus and Wurtz for passing air through 

 fluidified gelatin consists in transmitting the air through a tube con- 

 tracted at the end, whereby fine bubbles are produced. Frothing is 

 prevented by adding a drop of sterilized oil to the gelatin. The 

 apparatus consists of a glass tube closed at the lower end and measuring 

 40 mm. broad by 20 cm. high. |,Tho diameter of the lower part is 

 reduced to 15 mm., and herein 10 cm. of gelatin are placed. In the 

 upper end, also contracted, is inserted a glass tube, the end of which 

 reaches right to the bottom, and is there much reduced in size. Through 

 this tube the air passes, and those germs which are not caught up by the 

 gelatin are entangled in sterilized cotton- wool, a plug of which is placed 



♦ Amer. Mon. Micr. Joum., ix. (1888) pp. 77-8. 

 t Comptes KenduB, cvi. (1888) pp. 1558-9. 

 % Ann. Insfit. Pasteur, 1888, p. 171. 



