298 



Journal of Applied Microscopy. 



back to back, and hence requires only a minimum of the reagent. The cap in 

 this form does not fit closely enough to keep absolute alcohol and xylol, but 



does very well for the other 

 W iiiiiilHBIiSHf alcohols and stains. The 



form shown in Fig. 3 B is the 

 best for absolute^ alcohol and 

 xylol, but even with this it is 

 better to put a little vaseline 

 or glycerine on the cover to 

 prevent any evaporation. 

 Wide-mouthed bottles, though 

 not so convenient, give just 

 as good results. 



The other pieces of ap- 



Fig. 3. 



paratus mentioned need no comment. By consulting a catalogue, which will be 

 furnished by any dealer, the beginner can determine what he needs to buy, and 

 what he can find substitutes for, if it is necessary to be very economical. 



REAGENTS. 



It would require entirely too much space to even enumerate the reagents 

 which are occasionally used in a fully equipped university laboratory. The fol- 

 lowing list includes only those which are used constantly. The quantities given 

 indicate about what the average student uses in a three-months course in 

 methods. Nearly all the stains, however, would last for a year if properly used. 



Killing and Fixing Agents. — Commercial alcohol (about 95 per cent.), 

 2 liters; absolute alcohol, 200 cc; ether, 50 cc; chromic acid, 10 g.; corrosive 

 sublimate, 10 g.; glacial acetic acid, 25 cc; hydrochloric acid, 50 cc; picric acid, 

 5g.; chloroform, 50 cc; [osmic acid, 1 per cent, solution in water, 100 cc. This 

 is extremely expensive, and not necessary except for the most delicate work]. 

 Formulae for making killing and fixing agents from these materials will be given 

 later. 



Stains. — Only a few of the most important stains are given in this list. In 

 general, one should have enough of a stain to stand about two inches high in 

 the Stender dish, or bottle in which the staining is to be done. The theory and 

 practice of staining will be discussed in a future paper. 



Delajiehfs Hirfuatoxyliu. — To 100 cc. of a saturated solution of ammonia 

 alum add, drop by drop, a solution of 1 g. Haematoxlyn dissolved in 6 cc. of 

 absolute alcohol. Expose to air and light for one week, then filter. Add 25 cc. 

 of glycerine and 25 cc. of methyl alcohol. Allow to stand until the color is 

 rather dark. Filter, and keep in a tightly stoppered bottle. The solution should 

 stand for two months before it is ready for use, but, if needed immediately, the 

 " ripening," which is brought about by the oxidation of haematoxylin into 

 haematin, may be secured in a few minutes by a judicious addition of peroxide 

 of hydrogen. 



Mayer s Hcvmalnvi. — Dissolve with gentle heat 1 g. of haematoxylin in 

 5(»cc. of 05 per cent, alcohol; add a solution of 50 g. of alum in a liter of dis- 



