Neutral Stains 243 



precipitated compound stain and of dissolving it in some solvent 

 other than water. Jenner's stain is still called for occasionally. 

 Although it is markedly inferior to the modern type of blood 

 stains when used fresh, it does polychrome on standing in methan- 

 olic solution, and this fact undoubtedly explains its continued use. 



Combining Jenner's procedure with the Nocht stain was the 

 next logical step and was taken independently by Renter (1901) 

 and by Leishman (1901), The method thus introduced was 

 briefly to foUow Nocht's technic of combining eosin with poly- 

 chrome methylene blue, but then to filter off the precipitate and 

 to redissolve it in methyl alcohol, not adding further water until 

 the moment of applying the stain to the blood films. 



Modern blood stains are in general modifications of Leishman 's, 

 differing only in detail. Wright's modification (1902), the one 

 most used in America, (see Mallory and Wright, 1924, p. 170) 

 differs from Leishman's only in that he prepared polychrome 

 methylene blue by heating for only an hour in flowing steam, 

 whereas the Leishman technic calls for twelve hours at 65°C, with 

 subsequent standing for ten days. 



Previous editions of this book have contained directions for pre- 

 paring Wright stain. It is, in fact, perfectly possible for a labora- 

 tory worker to prepare a blood stain of this type that gives excel- 

 lent results; and the technic of doing so is not specially difficult 

 to one who has the necessary experience. Nevertheless, it has 

 proved that the directions given have not yielded uniformly de- 

 pendable results. It is desirable to have exactly the right amounts 

 of acid and basic dye present to combine without much excess of 

 either; and the relative amounts called for on theoretical grounds 

 do not always yield best results in practice. Moreover, spectro- 

 photometric control during polychroming seems to be necessary 

 to attain a uniform product, and the average laboratory worker 

 does not have the necessary facilities. Furthermore, this stain, 

 either in powdered form or dissolved in methyl alcohol, may be 

 purchased from stain companies at present, usually more uniform 

 in quality than can be made up by the user. Accordingly, 

 directions for its manufacture seem hardly called for here. 



Balch's modification calls for a polychrome methylene blue pre- 

 pared by standing 10 days with precipitated Ag20. Hastings 

 modification (1905) differs from that of Wright or Leishman in 

 that the polychrome methylene blue is neutralized with acetic 

 acid, and an unpolychromed solution of methylene blue is mixed 

 with it before eosinating. It is interesting, as a matter of fact, to 

 note that the method of preparing Wright stain followed by some 

 stain manufacturers is more like that of Hastings than like that of 

 Wright. In general American manufacturers sell the same prod- 

 uct as "Wright stain" and as "Hastings stain"; perhaps it should 

 all be known by the latter name. Lillie (1944a) has recently 

 suggested the use of a methylene blue polychromed by heating 



