NOTE, 
A NEW METHOD OF PARAFFIN INFILTRATION.— In preparing 
material for the microtome a- certain amount of difficulty is usually experienced 
in ' passing from absolute alcohol to paraffin. The ordinary method is to employ 
a clearing agent, such as xylol, chloroform, bergamot oil, or cedar-wood oil, which is 
miscible with both absolute alcohol and paraffin. 
Unless, however, the transition from (i) the alcohol to the clearing agent, and 
(2) from this to the paraffin, is very gradual, satisfactory sections are not obtained. 
A similar difficulty arises in the previous process of dehydration when effected by 
passage through a series of alcohols of increasing strengths, and good results are usually 
only obtained by using a series, the members of which differ not more than 5 per cent, 
to 10 per cent, one from another. 
A much more satisfactory method, involving only one change, and one to be 
recommended to the worker who has more than one ‘ job ’ on at a time, is to employ 
glycerine. The material after fixing and washing is placed in 10 per cent, glycerine 
and left open to the air in a convenient place to concentrate. At the end of two 
or three days the water will have evaporated away, an(} the material is left in nearly 
pure glycerine, which is easily and quickly replaced by absolute alcohol. The process 
of dehydration has been accomplished without any sudden change from a lower to 
a higher concentration, and the loss of water has been a uniform process. 
It occurred to the writer that a similar method might be devised for the infiltration 
process which, if successful, would lead to equally satisfactory results. What 
was wanted was a solution of paraffin wax, corresponding to the 10 per cent, 
glycerine, which could be made to evaporate slowly and finally result in pure 
paraffin. The following method has been used at Wisley with some success on such 
material as soft-rot of turnips and Peronospora parasitica on Capsella stems. Mr. F. T. 
Brooks, who tried the method, has informed the writer that excellent results were 
obtained with such material as anthers prepared for cytological work. The method 
is as follows : 
A small quantity of paraffin is melted in the oven and then poured into 
a graduated glass bottle which has been kept warm. Twice the volume of xylol is 
added, and then three times the volume of absolute alcohol. The bottle thus 
contains a liquid (at the oven temperature) made up of one part by volume of 
paraffin wax, two parts of xylol, and three parts of absolute alcohol. The liquid 
solidifies at room temperature and must be kept in the oven. Material in absolute 
alcohol is warmed in the oven for a few hours and then transferred to a tube of the 
paraffin mixture and left tightly corked for twenty-four hours. 
[Annals of Botany, Vol. XXXVI, No. CXLIV, October, 1922.] 
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