ACTINOMYCOSIS. 441 



minutely than by simply observing the cut surfaces of organs or growths. 

 And, further, it affords a means of rendering permanent many of the 

 instructive appearances observed at the autopsy, without preserving the 

 whole structure in the form of a museum specimen. Very satisfactory 

 results can be obtained with material hardened either in spirit or Miiller's 

 fluid. The fresh material is cut with a large, very sharp knife into slices 

 about a quarter of an inch, or less, in thickness. These slices are placed 

 between filter-paper in large porcelain dishes, such as are employed for 

 photographic purposes, and well covered with the hardening solution, 

 which should be frequently changed. By covering the slice with a small 

 sheet of glass, which is lightly weighted, any curling or turning up of the 

 edges is prevented, and the slice not only kept flat, but hardened with 

 smooth sur:^aoes. Several weeks are required for hardening in Miiller's 

 fluid. The slices, after a short time in water, are placed in gum, and 

 then frozen and cut ; the slices which are hardened in alcohol are soaked 

 in water until all trace of the spirit has been removed. A large micro- 

 tome on the Brace model is used to freeze and cut the sections. But in 

 some cases it will be found better to embed the slices in celloidin, and 

 cut' under alcohol with a large microtome of Jung's pattern. The 

 sections are carefully removed from the blade of the knife with a large 

 camel's-hair brush, and in the case of frozen sections floated in water. 



The next process is to float a section out in spirit, and with the 

 camel's-hair brush to unfold it and spread it out on a sheet of glass. 

 The glass with the section is lifted out and examined, and if the section 

 is sufiiciently thin, transferred to the staining solution. In the same 

 way the section is passed through the various stains, as it should be 

 prevented from rolling up or folding in the dye, or it may not be evenly 

 stained throughout. Modifications of this process will suggest them- 

 selves, such as pouring off the dye and leaving the section spread out at 

 the bottom of the dish, and then using the same dish for the next 

 process. The sections are so easily injured, that it is better, as much as 

 possible, to avoid handling them. If the sections are only a few inches 

 in diameter, such as transverse sections of the anterior portion of the 

 tongue of an ox, they can readily be transferred from dish to dish by 

 means of a large spatula, made by soldering a piece of sheet German 

 silver to thick copper wire. 



To stain them employ carbolised fuohsine and picric acid, or alum 

 cochineal, or logwood and orange-rubin. The processes of staining are 

 precisely the same as with ordinary sections ; but, from their unusual 

 size, experience and practice are required in their manipulation. 



When the section is dehydrated, it is ready to be cleared in clove-oil. 

 The glass on which it is to be permanently mounted should be selected 

 without scratches or flaws, and thoroughly cleaned and polished. It is 

 slipped under the section, which is evenly spread out upon it, and then 

 lifted out of the dish. The excess of spirit is drained off, the glass 

 placed on a level surface, and clove-oil poured on the section. It is left 

 until completely clarified ; the clove- oil, as much as possible, drained off, 

 and the rest entirely removed by gentle pressure with several thicknesses 



