2452 Journal of Applied Microscopy- 



New Method of Fastening Celloidin-Embedded Objects to 



the Block. 



After following for several years what were to me the most commendable of 

 the various details set forth in books and journals in reference to celloidin- 

 embedding and the relation of celloidinembedded objects to blocks, I have 

 devised a plan of fastening such objects to the block which very much simplifies 

 their handling. I have found this method very successful, and, since testing its 

 efficiency, I have again searched the literature at my command but fail to find 

 that the method has been described, so I report it as new. 



The method is very simple. Remove the celloidin-embedded tissue from the 

 alcohol in which it has been preserved and dry it by blotting with filter paper 

 and completing the drying by letting it lie upon the table with the side which is 

 to be next to the block upward. The drying does not need to be so thorough 

 as to cause the slightest shrinkage or distortion of the object. Then take up the 

 section between the thumb and forefinger or with forceps and dip the side which 

 is to be applied to the block into ether contained in a small Stender dish and 

 keep it in contact with the ether for 10 to "20 seconds. This will soften the cel- 

 loidin. Then transfer it quickly to a dry block and press down upon it for one- 

 half to one minute. It is now ready to be clamped into the holder, and by the 

 time it is adjusted to the knife it will be so firmly adherent that it will not spring 

 or be loosened by cutting. When enough sections have been cut, remove the 

 tissue from the block and put it into the alcohol. Only 40 to 80 seconds will be 

 consumed in fastening the tissue to the block exclusive of the drying, which 

 must be done in any event. The whole process need not take more than 2 to 3 

 minutes. 



In order to follow this plan it is necessary to embed by putting the pieces of 

 tissue into thick celloidin in a dish, such as a Stender dish, with the side from 

 which you wish to cut downward, and letting the celloidin slowly harden around 

 it. When sufficiently hard, cut the embedded tissue out and put it into 80 per 

 cent, alcohol to preserve until it is wanted for cutting, when it is put upon the 

 block as above described. The advantages of this method are as follows : 



1. Only one block for each microtome in use is needed. Thus the problem 

 of blocks is almost entirely done away with. 



2. It greatly simplifies the storage of the embedded objects. 



3. It necessitates the embedding in dishes, which is always the best. 

 Experiment Station, Ames, Iowa. JOHN J. Repp, V. M. D. 



