MICROCHEMICAL TESTS 287 



to slide with a mixture of 50 per cent, alcohol with a few drops 

 of glycerin and albumen, using .the alcohol as you would water ; 

 drain the slides dry. llemove wax in xylol, bring to 70 per cent, 

 alcohol. Stain sections in Ehrlich's hematoxylin for five or ten 

 minutes. Blue in tap water substitute, §1429 bis. Pass to a 2 per 

 cent, solution of potassium iodide saturated with iodine (a Lugol 

 solution) ; leave five minutes ; pour away, wipe around slide, and 

 dehydrate in absolute alcohol saturated in iodine. Clear in oleum 

 origanum cretici for about ten minutes. Mount in origanum balsam. 

 Such preparations should keep for years without fading much. We 

 have some slides of human placenta which after twenty years 

 still show the glycogen. 



This is described by Lison as " Methode de Langhans, variante de 

 Carleton." It was, however, used in this form by Jenkinson and S. G. 

 Scott previously. We do not know the exact origin of this variation. 

 It was pubhshed in this text-book in the 8th edition. 



It is not specific, since amyloid and certain proteid granules take the 

 colour as well. Spit on one slide and use it as a control, § 670, 



669, Ehrlich's Gum Iodine. Dissolve 50 grm, of gum arabic 

 in 100 c.c. of distilled water. The gum should be put in a net bag 

 or the solution filtered. Add 1 grm. of iodine dissolved in a little 

 water in which 3 grm. of potassium iodide have been dissolved 

 previously. Fix material in alcohol ; for Protozoa, smear, fix 

 in alcohol and add gum glycerin, apply coverslip after about one 

 quarter of an hour. Glycogen and paraglycogen brown. The 

 preparations are semi-permanent, 



670, Best's Carmine Stain. Material is fixed as for the iodine 

 method and may be imbedded in celloidin. If paraffin sections 

 are used the slide must be placed in 1 per cent, celloidin overnight, 

 drained and allowed to dry partly, and then plunged into chloro- 

 form and absolute alcohol (equal parts), then treated as for 

 celloidin sections. Transfer through alcohols 90 per cent, and 

 70 per cent, to water. Stain in Elu'lich's or iron ha^matoxylin 

 as usual, but differentiate in acid alcohol. Then proceed to 

 Best's carmine stain {Zeit. f. mikros., Bd. xxiii). Make up this 

 stock carmine solution : — 



Carmine , . . , . .2 grm. 



Potass, carbonate , . , . .1 grm. 



Potass, chloride , . . , ,5 grm, 



Aq. dest, . . , , , ,60 c.c. 



Boil gently for a few minutes ; cool. 



Add strong liq. ammon, 20 c,c. Keep this solution in a well- 

 stoppered bottle in a cupboard. It may go bad in a month 

 during summer. 



