LEAD AND COPPER 23 



1929) . This procedure depends on the formation of a yellow precipi- 

 tate of lead chromate when lead-bearing tissue is fixed in Regaud 

 fluid (20 ml. of 3% potassium dichromate plus 5 ml. formalin) . Lison 

 ( 1936, page 101) has discussed this method as well as the test based 

 on precipitation of the sulfide, and rather favors the former. Oka- 

 moto and Utamura (1938) employed 2^-dimethylaminobenzylidene 

 rhodanine to produce a reddish-violet precipitate with copper in tis- 

 sues, a reaction given by gold, silver, and other metals (see pages 

 26, 28, and 29) . 



Mallory and Parker (1939) described a method using hema- 

 toxylin and another employing methylene blue which would visual- 

 ize both lead and copper. The methylene blue technique was particu- 

 larly recommended for photomicrography of lead because of the in- 

 tense blue color developed. 



In a study of the histological distribution of copper in the blowfly, 

 Waterhouse ( 1945) found that the only reagent which could be used, 

 of those tested, was sodium diethyl dithiocarbamate, which formed a 

 yellow product with copper. Waterhouse's technique was to drop a 

 0.1% aqueous solution on the fresh tissue followed by a drop of con- 

 centrated hydrochloric acid. The acid allowed greater penetration 

 of the reagent into the cells. Iron can interfere with this test by the 

 formation of a brown carbamate; however, the reagent can detect 1 

 part of copper in 100 million and its sensitivity to iron does not 

 approach this. 



Mallory and Parker Hematoxylin Method for 

 Lead and Copper 



SPECIAL REAGENTS * - 



Hematoxylin Reagent., Dissolve 5-10 mg. hematoxylin in a few 

 drops of 95% or absolute alcohol and add 10 ml. freshly filtered 

 2% dibasic potassium phosphate. 



PROCEDURE 



1. Fix tissue in 95% or absolute alcohol (formalin may be used 

 for copper) . 



2. Prepare celloidin sections as usual. 



3. Stain sections for 2-3 hr. at 54°. 



4. Wash in several changes of tap water 10 to 60 min. 



