﻿BRIEFER ARTICLES 



CHLOROFORM AS A PARAFFIN SOLVENT IN THE 

 IMBEDDING PROCESS 



In a recent number of this journal Land 1 describes an improved 

 method of replacing the paraffin solvent with paraffin, in which he calls 

 attention to certain difficulties encountered in the use of xylol as a 

 solvent, and offers some suggestions by which these difficulties may be 



The writer is somewhat surprised to find that xylol is so extensively 

 used as a paraffin solvent in the process of infiltration, and for this 

 reason he is tempted to describe the method that he has used for a num- 

 ber of years. In the first place, judging from the writer's experience, the 

 best way, or at least one of the best ways, to avoid the difficulties men- 

 tioned by Land in the use of xylol is to do away with the xylol altogether. 

 Nineteen years ago the writer discarded the use of xylol. In its place 

 he used chloroform, and he has been convinced that this solvent is 

 superior to xylol. His method is as follows: We assume that the 

 material has been carefully and thoroughly dehydrated by passing 

 through the grades of alcohol, beginning with very low percentages, 

 depending upon the character of the tissue. In dehydrating very soft 

 objects one may begin by adding a few drops of alcohol at a time until 

 a strength of 10 or 15 per cent has been reached. I have found this a 

 safe thing to do in the case of objects like the seaweed Champia panula. 

 Some objects, however, may be placed directly from water into 20 per 

 cent alcohol. It does not seem that standing overnight in any of the 

 weaker grades of alcohol injures the tissues in the least. 



After the specimens have been thoroughly dehydrated (I refer 

 chiefly to material for morphological and cytological purposes), they are 

 placed in a mixture of equal parts of absolute alcohol and chloroform, 

 where they should remain for 2-3 hours or longer. When thrown into 

 this fluid the specimens float, but in a short time they sink to the bottom 

 of the vessel. No injury results if the specimen be allowed to remain in 

 the chloroform and alcohol overnight or longer. Next the specimens are 

 placed in pure chloroform, where they remain for 2-12 hours, depending 

 upon the size of the specimens, the nature of the tissue, and to some 



1 Land, W. J. G., Microtechnical methods. Bot. Gaz. 59:307-401. 1915- 

 2 5i) [Botanical Gazette, vol. 61 



