HISTOLOGIC TECHNIC 761 



(b) Embed in celloidin, the different solutions of which should 

 be made up in 95 per cent, alcohol (see Kingsbury, Anat. Rec., 

 5, 6, 1911). 



Technic for Demonstrating Chromaffin Granules. Chromaffin 

 material ('pheochrome' granules; adrenin granules) is highly susceptible 

 to solution by acids. When preserved the chrornaffin granules react to 

 chromium (acid and solutions of salts) and stain light brown. The 

 best method for their preservation is Kelly's fluid (see page 728), which 

 coincidently stains the granules. Paraffin or celloidin sections may be 

 stained with various nuclear dyes for the clear differentiation of the 

 nuclei. 



Oelloidin-paraffin Method (Apathy; Ztschr. wiss. Mikr., Bd. 

 XXIX, 1912, S. 449-515). This method obviates the difficulties en- 

 countered in sectioning hard and brittle objects, e.g., chitin, and eggs 

 with yolk. 



1. Place thoroughly dehydrated tissues in ether-alcohol for at least 

 five hours. 



2. Thin celloidin (2 per cent, solution) for twenty-four hours. 



3. Thick celloidin (4 per cent, solution) for twenty-four hours. 



4. Pour into a paper embedding box or a glass dish, and harden in 

 chloroform vapor for twelve hours. 



5. Trim the block quickly, leaving a few millimeters of celloidin on 

 each side of object, and place in test tube of chloroform for twelve 

 hours. 



6. Transfer to tube of following oil mixture until the block be- 

 comes clear and sinks: 



Chloroform, by weight 4 parts 



Oil of origanum, by weight 2 parts 



Oil of cedar wood, by weight 4 parts 



Absolute alcohol, by weight .'.... 1 part 



Carbolic acid crystals, by weight 1 part 



(Put small amount of dried sodium sulphate into bottom of 



test tube to take up the water brought into the mixture by the 



celloidin.) 



7. Wash cleared block in three or more changes of benzol; this re- 

 moves the oils and alcohol, and prepares for paraffin filtration. 



8. Embed in paraffin, section and mount as in ordinary paraffin 

 technic. (See aho Kornhauser, Science, July 14, 1916, 57-58.) 



48 



