Journal of Applied Microscopy 



and 



Laboratory Methods 



Volume VI. APRIL, 1903. Number 4. 



On Embedding in Celloidin. 



In cutting sections of tissues which have been embedded in celloidin accord- 

 ing to the method now in general use, certain difficulties are often met, which 

 are due partly to inaccurate preparation of the solutions of different strengths, 

 partly to insufficient infiltration owing to leaving the tissues too short a time in 

 these solutions. Thus, for example, in cutting portions of the alimentary tract, 

 one is frequently forced to cut thicker sections than he would like, owing to the 

 fact that the sections tear apart in the tela submucosa. By the use of the fol- 

 lowing method many disadvantages may be overcome, and I advise its use in all 

 those cases in which accuracy of results is of sufficient importance to justify the 

 greater expenditure of time and care. 



Very satisfactory results were obtained with this method with nerve tissue 

 that had been in Miiller's fluid several years. By the old method it was very 

 often necessary to fortify the sections to keep them from crumbling and break- 

 ing, but the tissues are so thoroughly penetrated by this method, that I have 

 stained by Weigert's method sections cut at lO/i without taking any additional 

 precautions to keep the sections intact. 



Schering's granulated celloidin, or better, the moist cake celloidin is used. 

 In the latter case, the cake is cut into thin strips and allowed to dry in a glass 

 dish protected from the dust. When dry, it has a yellowish tint, and is very 

 hard. One cake of Schering's celloidin when dry weighs from 28 to 30 grammes. 

 Ten wide-mouthed, cork-stopped bottles should be cleaned and thoroughly dried iox 

 the celloidins. The different solutions are made up so that each 100 c. c. con- 

 tains two, four, six, etc., up to twenty grammes by weight of celloidin. Tissue 

 that has been thoroughly dehydrated, and passed through absolute alcohol and 

 ether, is passed through the graded celloidins, being left twenty-four hours in 

 each solution. If to be cut immediately, the tissue is mounted on a block and 

 hardened in chloroform for from fifteen to twenty minutes, or in eighty per cent, 

 alcohol for several hours. If it is to be kept for some time, the tissue should 

 be removed from the twenty per cent, celloidin with a thick layer of celloidin 

 surrounding it, and dropped into chloroform to harden, after which it is kept in 

 equal parts of ninety-five per cent, alcohol and glycerine. 



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