166* PREPARATION AND MOUNTING 



under water with a fine camel-hair brush very gently, so as 

 to remove the precipitates of the gold salt. Sections of a 

 cornea so prepared may be made on the finger by a sharp 

 razor, and must be examined and kept in glycerine. 



LIVER, KIDNEY, SPLEEN, LUNG, &c. Some parts which 

 are too soft to be cut into sections in their ordinary state, 

 are usually hardened by being steeped in a solution of 

 chromic acid, about two grains to an ounce of water. This 

 will take some weeks according to the substance, and the 

 solution should be changed now and then. Dr. Bastian, for 

 mounting, uses Canada balsam partially dried to dispel the 

 turpentine, and then diluted to necessary consistence with 

 benzole. The section being cut from the hardened organ is 

 washed in spirits of wine for some minutes, then a drop of 

 liquid carbolic acid is placed on the slide where the speci- 

 men is to be mounted. Take the specimen and let its edge 

 touch a piece of blotting-paper, and place it upon the 

 carbolic acid, which will render a thin section transparent 

 in about a minute. Remove the superfluous acid with 

 blotting-paper, when two or three drops of chloroform must 

 be poured upon the section and remain one minute. Drain 

 off and place upon the object the solution of Canada balsam 

 in benzole, and apply the thin glass cover. Or place the 

 object in ordinary spirits of wine for about a minute to wash 

 it, then remove into absolute alcohol for five minutes. Lay 

 it upon the slide and drain, cover with one or two drops of 

 benzole for about a minute, tilt to drain off, and proceed as 

 above. 



Both these methods are good, but the first does not 

 always answer for sections of liver, as they generally are 

 acted upon by carbolic acid ; but few other tissues are thus 

 affected. Tinted specimens seem equally safe when mounted 

 in this way. 



SECTIONS OP BRAIN AND SPINAL CORD. Dr. Bastian 

 gives his experience of these tissues as follows : I immerse 

 the section for about ten minutes in absolute alcohol diluted 

 with eight per cent, of water, then place upon the glass 



