410 HISTOLOGY. 



alcohol cannot be used twice. The section is mounted by taking it from 

 the oil upon a spatula, and transferring it to the center of a slide upon which 

 it should be spread out flat. The oil around it is wiped away and several 

 layers of filter paper are placed directly upon the section; the ringer is 

 rubbed over them so that the section is further flattened. Remove the 

 filter paper, and mount in damar as with paraffin sections. 



The handling of large numbers of celloidin sections is facilitated if 

 they are placed in a perforated cup which fits into another ordinary cup. 

 The ordinary cups contain the various reagents and the sections are trans- 

 ferred from one to the other in the perforated cup. The latter may be 

 obtained as Hobb's tea infusers, and the solid lemonade cups are of proper 

 size to receive them. 



GENERAL STAINS. 



Haematoxyline and eosine. Haematoxyline is a dye obtained from 

 logwood, which stains nuclear structures blue. Eosine is an aniline dye 

 staining protoplasm red. This and all aniline dyes used in histological 

 stains should be prepared by Griibler in Germany. 



There are many solutions of haematoxyline among which is the fol- 

 lowing : 



Haematoxyline crystals i gr. 



Saturated aqueous solution of ammonia alum 100 cc. 



Water 300 cc. 



Dissolve the crystals in the water, which may be heated, and add the alum 

 solution. Put the mixture in a bottle and drop in a crystal of thymol to 

 prevent the growth of mould. A loose plug of cotton is used for a stopper 

 and in this condition the solution is kept in the light for 10 days to ripen. 

 It changes color during this process of oxidation, after which it is ready for 

 use and is kept tightly stoppered. It deteriorates in a few months. If a 

 strong solution is desired the amount of water may be reduced. 



Another haematoxyline solution in common use is Delafield's. It is 

 made by dissolving 4 gr. of haematoxyline crystals in 25 cc. of 95 per cent, 

 alcohol, and then adding 400 cc. of a saturated aqueous solution of ammonia 

 alum. This is kept unstoppered for 3 or 4 days and then is filtered. 

 100 cc. each of 95 per cent, alcohol and of glycerine are added. It should 

 not be used until it has become dark colored by remaining in the light for 

 several days. Then it is to be filtered and tightly stoppered. 



Eosine is sold in two forms, one soluble in water, the other in alcohol. 

 In connection with the haematoxyline stain, a y 1 ^ to i per cent, aqueous 

 solution may be used; or a i per cent, solution of alcoholic eosine, made 

 in 60 per cent, alcohol. 



To stain with haematoxyline and eosine the sections are placed in the 



