62 Animal Micrology 



STAINING CELLOIDIN SECTIONS IN HEMATOXYLIN AND EOSIN 



The objects are killed, fixed, and preserved as usual in 70 per 

 cent, alcohol, and sectioned as in the above method. 



1. Fifty and 35 per cent, alcohol each 3 to 5 minutes. 



2. Delafield's hematoxylin, 10 to 30 minutes. 



3. Water 5 minutes. 



4. Thirty-five, 50, and 70 per cent, alcohol each 3 to 5 minutes. 



5. Acid alcohol until the celloidin which surrounds the object 

 shows but little of the stain. 



6. Seventy per cent, alcohol, barely alkaline (see chap, vi, 

 memorandum 10), until the red color caused by the acid is replaced 

 by bluish purple. 



7. Alcoholic eosin, 30 seconds to 1 minute. 



8. Ninety-five per cent, alcohol, 2 to 5 minutes. Clear in car- 

 bol-xylol and mount in balsam. 



NOTE. As time permits section other tissues by the celloidin method 

 and stain as above. 



MEMORANDA 



1. If Chloroform is Not at Hand, 80 per cent, alcohol will harden the 

 celloidin, although more slowly. 



2. The Length of Time that objects should be left in ether-alcohol 

 and the celloidin mixtures depends upon the size and density of the 

 objects. When time permits it is always best to leave them several days, 

 or even weeks in the mixtures of celloidin. For large objects such as the 

 medulla of a large brain this is a necessity. For an embryo of large size 

 months may be required. 



3. Blocks for Celloidin Mounting may be of wnite pine, glass, vulcan- 

 ized fiber or even a very hard paraffin. Cork should not be used 

 because it is liable to give or bend. The vulcanized fiber is the most 

 satisfactory. It may be purchased from dealers in the form of strips 

 which may easily be sawn to the necessary dimension. It is well to saw 

 several parallel cuts into the upper edge of the block to provide points 

 of attachment for the celloidin. 



4. Other Clearers may be substituted for carbol-xylol. One which 

 clears from 95 per cent, and which does not dissolve celloidin must be 

 chosen. Cedar oil is an excellent clearer as is also beech wood creasote. 

 Other good clearers are (1) origanum oil, (2) a mixture of oil of thyme 

 (3 parts) and castor oil (1 part), and (3) Eycleshymer's clearing fluid 



