126 SPECIFIC EXAMPLES OF SLIDE-MAKING 



higher melting point than 52° C. be employed and that embedding be con- 

 ducted exactly at this temperature. It is far easier to do this by the method of 

 an overhead heating light placed above a tube of paraffin than by thermo- 

 static control. It may be stated categorically that should the temperature be 

 permitted to rise above 56° C. it would be better to throw the preparation 

 away than to waste time endeavoring to section it. Paraffin sections are cut 

 from the block by the standard method, stranded, and caused to adhere to the 

 slide by egg albumen. These sections, however, may be lost because muscularized 

 tissues tend to absorb water very readily when in paraffin section, so that, if the 

 sections are flattened for a prolonged period in contact with large volumes of 

 warm water, they will tend to expand more than the surrounding wax with 

 the result that they will arch away from the glass support and inevitably be- 

 come detached while being deparaffinized. Therefore, it is recommended that, 

 as soon as the sections are flattened, they should be pressed to the slide with 

 a piece of wet filter paper, rolled into position with a rubber roller, and dried 

 with the maximum possible speed. 



As soon as they are dried, the sections are deparaffinized by the usual tech- 

 niques and taken down to distilled water where they may remain until one is 

 ready to stain them. Celestin blue B is selected as the nuclear stain in this in- 

 stance because the contrast of muscularized tissues is far better brought out 

 with the aid of a picro-contrast than by any other method. These picro-contrasts 

 are, however, so acid that hematoxylin-stained nuclei are often decolorized in 

 the course of counterstaining. The formula for the nuclear stain is given on 

 page 21. The solution presents no difficulties of preparation and need not be 

 rejected if it shows a slight precipitate at the bottom. The sections are passed 

 directly into it from the distilled water and allowed to remain until an exam- 

 ination under the low power of the microscope shows the nuclei to be stained 

 clearly and deeply. It is very difficult to overstain in this solution; though the 

 time specified in the formula given is from 5 minutes to 1 hour, no damage 

 will be occasioned should the sections remain overnight in the staining solution. 

 After they are removed from the staining solution, they are rinsed in distilled 

 water and accumulated in a jar of either distilled or tap water until it is time 

 to counterstain them. 



The solution of van Gieson (see p. 23) should be used for counterstaining. 

 This stain requires little or no differentiation, so that the sections may be placed 

 in it and examined from time to time until the muscles are seen to be stained 

 a very bright red against a connective-tissue background of yellow. If a small 

 quantity of red is picked up by the connective tissues, it will be removed in 

 the process of differentiation. The time is not critical, but that given in the 



