CELLOIDIN INFILTRATION. ^# 



cellular and hence very difficult to cut, when infiltrated with this 

 material are supported in such a manner as to render the production 

 of thin sections a very easy matter. 



Bayberry tallow is found in commerce in various grades. The best 

 is white, clean, and of a consistency about equal to that of hard mut- 

 ton tallow. It is instantly soluble in benzol, and dissolves rather 

 slowly in alcohol. 



Having selected a piece of alcohol-hardened tissue for cutting, care- 

 fully wipe it dry with blotting-paper and drop it into a capsule 

 containing melted bay berry tallow. In order to render the tallow 

 sufficiently fluid, and yet prevent the heat from becoming great 

 enough to injure the tissue, the capsule should be set over a water- 

 bath. Bubbles immediately arise as the spirit is vaporized and the 

 tallow gradually fills the interstices of the tissue. If the latter be of 

 a somewhat dense character it will be best, before placing it in the tal- 

 low, to allow it to remain for an hour in pure benzol which, evaporating 

 at a very low temperature, gives more ready admission to the infiltrat- 

 ing medium. 



The length of time required for complete infiltration will depend 

 upon the density and the degree of heat employed. Usually from ten 

 to thirty minutes will suffice. 



The tissue, having become sufficiently infiltrated, is lifted out with 

 the forceps, placed on a cork support, and allowed to cool. It is then 

 cut, either free-handed or with the microtome, and ivithout alcohol. 

 The dry sections, resembling tallow or wax shavings, are brushed into 

 a saucer of pure benzol when in a moment the tallow will be dis- 

 solved from the tissue. The sections are then lifted with a needle 

 singly into a saucer of alcohol to remove the benzol. Afterward, 

 they are transferred to a bottle of spirit, and labelled for future use. 

 They will keep indefinitely. 



This process is peculiarly advantageous with such tissues as lung, 

 pancreas, cerebellum, intestine, etc., where the structures require 

 support only while they are being cut. The infiltrated blocks of tis- 

 sue can be kept dry until such time as they may be wanted. 



CELLOIDIN INFILTRATION. 



Certain structures require permanent support, i. e., not only while 

 being cut, but during the subsequent handling of the sections. The 

 celloidin infiltrating process is best adapted to such material. Con- 

 siderable time is needed for the successful employment of the process, 

 but results can be secured that cannot be equalled with any other 

 method. 



