MOUNTING PARAFFIN SECTIONS 263 



the term mikron is applied to .001 mm. and the above thick- 

 ness would be called 5 and 10 mikrons. 



Mounting Paraffin Sections.— The paraffin sections are 

 made to adhere to the glass slips by means of albumin water. 

 The stock solution of this is made as follows: Shake together 

 equal parts of white of egg and distilled water and add to this 

 a pinch of salicylate of soda to keep it from spoiling. For 

 use add one drop of the stock solution to one ounce of distilled 

 water. This dilute solution will be referred to as albumin 

 water. 



Rinse thoroughly and wipe dry a glass slide that has been 

 kept in a saturated solution of bichromate of potash in strong 

 sulphuric acid. Place at the center of the slide a drop of albu- 

 min water and with a dissecting needle drag the drop out in 

 a thin film covering the space that is to be occupied with the 

 sections. The albumin water should stay just where you put 

 it without creeping away in the least. If it does creep the slip 

 is not clean enough and it should be rinsed off and rubbed 

 with a cloth moistened with alcohol. Cut the paraffin ribbon 

 up into the desired lengths and lay these on the film of albumin 

 water, keeping the glossy side of the ribbon down, namely the 

 side that was down on the knife after cutting, for this side 

 adheres better to the slide than the other. When as many 

 sections have been put on as will fill out under the coverglass, 

 or a less number if so desired, warm the slip over a flame until 

 the ribbons lie perfectly flat and then draw away the albumin 

 water with filter paper; at the same time keep the pieces of 

 ribbon close together and properly lined up, and then place 

 the preparation where it can dry for an hour or so at a tem- 

 perature a little below the melting point of the paraffin. After 

 this stand the slip on end in a dish of xylene to dissolve away 

 the paraffin, and then in a dish of 95 per cent, alcohol to rinse 

 out the xylene, and after this the sections will be ready for 

 staining. If the sections have been at all blackened by the 

 osmic acid, as often happens, they should be bleached before 

 staining. To do this place the slide for a few minutes in a 



