334 NATURAL HISTORY OP OUR SHORES 



place a little weight, say a cover glass, on the object to keep 

 it submerged or, what is better, carefully pour a layer of 

 absolute alcohol on the surface of the oil. The object will 

 slowly sink into the denser medium, after which the alcohol 

 can be decanted, or, if there has been mixture, the object 

 can be placed in new oil of cloves. 



If, in " clearing," an object of any kind retains an opaque 

 spot, which does not disappear, even in half-an-hour's 

 soaking in the oil, dehydration has not been complete. 

 Put the object back into the absolute alcohol, and go 

 over the process afresh. 



All slides should be neatly labelled, with as plain a 

 gummed label as procurable. Some labels have heavy 

 ornamental borders. These are not suitable for a scientific 

 collection. 



Slides should be stored in trays in which they lie flat ; 

 racked boxes, in which the slides are on edge, are not good : 

 very often, in a cell mount, the object will gravitate to the 

 side. 



