BASED UPON EXPERIMENTS WITH THE BLOW-FLY. 347 



the tinger, and partly with a fine piece of stick like a lucifer-match 

 cut to a chisel edge. When the slide and ribbon are perfectly 

 dry, the imbedding material may be melted, and dissolved away 

 while hot, by a rapid flooding with benzoline,* which in its turn 

 can be washed oflf just as quickly with absolute alcohol. If the 

 specimen has been stained in bulk, oil of cloves should now be 

 applied, as recommended by Dr. Lowne, the slide set on end to 

 drain for six hours, and the mounting completed with Canada 

 balsam. Sections, to be stained on the slide with Ehrlich's logwood, 

 have to undergo seven more processes than those stained in bulk,, 

 and the risk is proportionally increased. 



After they have been washed with alcohol to remove the 

 benzoline, they have (1) to be washed with methylated spirit; 

 (2) to be stained ; (3) to be plunged into acidulated water ; (4) to 

 be placed in running tap-water for thirty minutes. Then they 

 must be brought back to the dehydrated condition, for which 

 purpose we use (5) proof spirit ; (6) pure methylated spirit ; 

 (7) absolute alcohol. After this the oil of cloves may be applied, 

 and the mounting completed in the same way as for specimens 

 stained in bulk. 



Of the above seven processes, the second, third and fourth are 

 the most dangerous to the sections, though damage can generally 

 be avoided if adhesion be firm ; and with good sections it usually 

 is so firm, that a second staining, after the running water process,, 

 may be practised with safety. 



It will be found, on comparing the methods recommended in 

 this paper, with those described by Dr. Lowne in his book (pp. 93 

 to 98), that time and labour are saved and risk of failure 

 diminished. 



Thus (1) the preparation of the specimen by soaking in 

 chloroform or other agent is done away with altogether ; (2) the 

 time required for imbedding is reduced from " twenty-four hours 

 or longer" to a much shorter period, commonly to about 2| hours,, 

 and this object is effected at the temperature of 45° C. instead of 

 54° (130° Fahr.); (3) the removal of the imbedding material 

 from the slide, by soaking in turpentine for " from one to twenty- 

 hours," is replaced by a rapid flooding while hot with benzoline ; 

 (4) the removal of the turpentine by immersion in methylated 



* This has been used by other microtomists, but is objected to by 

 Dr. Lowne on account of its inflammability (p. 350). 



