APR] NOTES. 471 



NOTE A. 



Since writing the account of section-cutting on p. 434, 

 we have obtained more experience as to the practical work- 

 ing of Messrs. Caldwell and Threlfall's microtome there 

 mentioned. We find that it cuts more accurately and better 

 than any other microtome with which we are acquainted, 

 and can confidently recommend it to investigators and 

 teachers with large classes. In the Cambridge Laboratory, 

 it is driven by a small water engine and will cut at a rate 

 of 500 a minute, without detriment to the sections. 



NOTE B. 



Mr Threlfall, of Caius College, has recently elaborated 

 a method of mounting sections which in our opinion has 

 many important advantages over the shellac method. It is 

 as follows. Make a solution of pure india-rubber in benzine 

 or chloroform. Spread a thin film of this on a clean glass 

 slide, and allow it to dry. Arrange the sections on the 

 film y melt the paraffin ; allow the slide to cool, then 

 immerse the slide for a moment in benzoline (liquid 

 paraffin), which dissolves the paraffin, and mount in balsam. 

 The chief advantages of this method are that the sections 

 do not adhere to the india-rubber until warmed, and they can 

 be stained after they are fixed on the slide if necessary. 

 For the latter purpose, wash the benzoline away with 

 absolute alcohol ; treat with weaker alcohol ; stain ; return 

 to absolute ; clear with oil of cloves or kreasote, and mount 

 in balsam (vide Zoologischer Anzeiger, 1883). 



