320 NATURAL HISTORY OF OUR SHORES 



say an hour, take it out, and transfer it to the melted wax. 

 The wax must be taken off the fire before this, and should 

 be on the way to cooling, the top beginning to bear traces 

 of solidification. Keep it at this same gentle heat, just 

 near the stove, for some time, say an hour or two. (It may 

 now be left to go cold, if desired, and warmed up another 

 time.) 



While this is going on prepare some glass slips as follows : 

 Clean them well, and by means of a glass rod gently 

 smear one side (not the ends) with white of egg ; by pressing 

 the rod steadily across the slip a very thin and even layer 

 of albumen is thus put on. It is well to prepare a number 

 of slips at one time, placing them, supported by their ends, 

 prepared side downwards, for fear of dust, until they are 

 dry. It is well to mark with ink, on one corner, which is 

 the prepared side, for it is not visible. (The spare slides 

 can be stored for use later.) 



Now screw the microtome steadily to the table, turn 

 down the regulating screw an inch or so, and fill the well 

 with melted wax. As the wax cools from the sides there 

 will be a little hollow in the centre. Into this put the little 

 sponge, vertically, holding it in place while the wax cools 

 by means of the forceps ; let all cool to solidity. 



Now raise the regulating screw until a quarter of an inch 

 or so of the column of wax is exposed, and with a penknife 

 cut away a good bit of the wax from around the sponge, 

 only allowing a little ring to remain around it (this is to 

 avoid having to slice a lot of wax to no purpose) ; then 

 turn back the screw, and press the column back to where 

 it was. 



See that your razor is very sharp. Elevate the object 

 and cut off the top ; throw away this bit, and gradually 

 raise the object, slicing off a little at a time until the whole 

 of the contour of the sponge is seen, like a neat little pattern 

 in the cone of white wax. 



