110 METHODS OF MICROSCOPICAL RESEARCH. 



which evaporating leaves the specimen perfectly 

 embedded in a transparent and firmly gelatinous 

 matrix. 



Lee, in his invaluable Text-Book 1 treats of the 

 "theory of embedding" in a manner so exhaustive 

 and practical that the author ventures to quote 

 largely from his clever pages and tendering his best 

 acknowledgments. Lee, then, says, after referring 

 to the simplest methods of embedding : " A further 

 object is proposed in the case of the other (i.e., the 

 more elaborate) class of methods, which may be 

 designated methods of interstitial embedding or 

 infiltration methods. In these it is proposed to fill 

 out with the imbedding mass the natural cavities of 

 the object, in order that their lining membranes, or 

 other structures contained in them, may be duly 

 cut in situ, or, going a step further, it is proposed 

 to surround with the supporting mass not only each 

 individual organ, or part of any organ that may be 

 present in the interior of the object, but each 

 separate cell, or other anatomical element, thus 

 giving to the tissues a consistency they could not 

 otherwise possess, and ensuring that in the thin slices 

 cut from the mass all the details of structure will 

 precisely retain their natural relations of position. 

 Such a process of embedding is at the same time 

 practically a process of hardening, in so far as it 

 enables us to give to tissues a degree of firmness 

 that could otherwise only be obtained by the em- 

 ployment of chemical processes, such as prolonged 

 treatment with chromic acid and the like. The 



1 "The Microtomist's Vade Mecum " (page 162). J. & A. 

 Churchill. 



