36 MAKING FIXED FILMS 



jelly" (1) add 1 c.c. of a 1-per-cent solution of 

 theobromine, 1 0*7 c.c. of a 1-per-cent solution of 

 atropine sulphate, 1 c.c. of a 5-per-cent solution 

 of sodium bicarbonate, and 2*3 c.c. of distilled 

 water total, 10 c.c. 



The tube is steeped in boiling water until the 

 jelly melts and mixture is complete. The whole 

 is then boiled and a drop of the molten mixture 

 poured on to a microscope slide, where it is 

 allowed to cool and set. A drop of citrated 

 blood (1) is placed on to the centre of a cover- 

 glass, which is then inverted and allowed to fall 

 blood downwards flat on to the convex surface 

 of the jelly film on the slide. The blood spreads 

 out evenly between the jelly and cover-glass, and 

 the slide is placed in the 37 C. incubator for ten 

 minutes. It may then be examined with the 

 microscope. The cells should be admirably spread 

 out one by one ; the polymorphonuclear leucocytes 

 should nearly all be burst; but the lymphocytes 

 in spite of the fact that they are unstained should 

 nearly all be seen to be exhibiting some phase of 

 mitosis. Because the jelly contains atropine many 

 of the figures may be asymmetrical. 



Fixation. In the bottom of a watch-glass place 

 a few drops of a saturated solution of osmic acid. 

 The slide should be inverted and allowed to rest 

 on the edges of the watch-glass with the jelly 

 film and cover-glass downwards, so that the fumes 

 of the osmic acid impinge directly on the cover- 

 glass. None of the osmic-acid solution should 



1 Theobromine is not quite soluble to 1 per cent, but the solution 

 should be shaken up and then added. It will dissolve in the jelly 

 into which it is mixed. 



