CHAPTER X 

 THE CELLOIDIN METHOD 



The celloidin method is used more extensively by zoologists than 

 by botanists. Where many mounts are necessary and only a single 

 section is needed for each mount, the method is to be recommended, 

 if the sections cannot be cut equally well without any imbedding. 

 All the sections can be stained and cleared at one time, so that, in 

 making the individual mounts, it is necessary only to place a section 

 on the slide and add a drop of balsam and a cover. Another advan- 

 tage, and the only one so far as the botanist is concerned, is that 

 hard roots and stems, which cannot be handled by the paraffin 

 method, are cut easily in celloidin. Where serial sections are neces- 

 sary, as in most morphological and cytological work, the method is 

 too tedious to be worth even a trial, unless the sections cannot be cut 

 in any other way. Besides, most of the more valuable stains color 

 the celloidin matrix, and if the matrix be removed, the more delicate 

 elements may be displaced or even lost. 



Celloidin and collodion are forms of nitro-cellulose. They are 

 inflammable, but do not explode. Schering's celloidin, which is only 

 a collodion prepared by a patented process, is in general use for 

 imbedding. Granulated and shredded forms of celloidin are on the 

 market, but the tablets are more convenient. Directions for making 

 the various solutions accompany the celloidin. To make a 2 per 

 cent solution, add to one tablet enough ether-alcohol to make the 

 whole weigh 2,000 g. To make a 4 per cent solution, add another 

 tablet, and to make a 6 per cent solution, add an additional tablet, 

 and so on. 



The collodion method was published by Duval 1 in 1879. Cel- 

 loidin was recommended by Merkel and Schiefferdecker 2 in 1882. 

 The principal features of the method are as follows: Material is 



1 Duval, Journal de I'anatomie, 1879, p. 185. 



2 Merkel and Schiefferdecker, Archiv fur Anatomie und Physiologie, 1882. 



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