4 

 20 MATERIALS AND PROCESSES OF SLIDE-MAKING 



For those, however, who do not wish to take the time for the latter prep- 

 aration, a working solution may be made directly in the following manner: 



Boil 2 Gm. borax and 1.5 Gm. of carmine with 50 ml. of water for 30 

 minutes. Cool and then add 50 ml. of 70 per cent alcohol. This solution 

 should be filtered after two or three days. 



METHOD OF USING THE SOLUTION PREPARED FROM THE DRY STOCK POWDER 

 IS AS FOLLOWS: 



1. Accumulate the objects in whatever percentage of alcohol is convenient. 



2. Make up a saturated solution of the dry powder in alcohol from 1,0 to 

 20 per cent stronger than that in which the objects are accumulated. 



3. Transfer the objects to stain until they have become a deep red color. 

 This will take from five minutes for an individual protozoan to over- 

 night for a medium-sized flatworm. 



4. Transfer the objects to 0.1 per cent hydrochloric acid in alcohol of the 

 same strength as that used for making up the stain. Let them remain in 

 this solution until they become pink and translucent. 



5. Dehydrate and mount the objects in the usual manner. This stain is not 

 only good, used in the manner described, for staining wholemounts but 

 is also much the best method of staining the nuclei in blocks of tissue 

 before sectioning il this technique is to be employed. 



Grenacher's alcoholic borax carmine is not very satisfactory when diluted 

 and used by the indirect method. For this purpose it is recommended that the 

 following be employed: 



Mayer's Carmalum: 

 Staining solution 



Boil together, for 1 hour, 2 Gm. of carmine and 5 Gm. of potassium alum 

 in 100 ml. of water. Cool and filter. 



This solution may be used exactly as Grenacher's alcoholic borax carmine 

 for wholemounts or blocks of tissue but it is less satisfactory for this purpose. 

 It is best used after great dilution for direct staining ol relatively large 

 invertebrates. 



METHOD TO BE EMPLOYED IS AS FOLLOWS: 



1. Accumulate the objects in distilled water. 



2. Dilute the stain with 5 per cent potassium alum to the required concen- 

 tration. The larger the object to be stained, the lower the concentration 

 of the staining solution should be. For a relatively small and thin object, 

 such as the prothallium of a fern, a dilution of about 10 to 1 is satisfac- 

 tory. For a large object, such as a liver fluke, the stain should be diluted 

 until it is only faintly pink. 



