DETECTION OF PHOSPHORUS COMPOUNDS. 55 



Solutions of both molybdic acids give, when treated with 

 phenylhydrazin hydrochloride an immediate blue reaction which 

 gradually deepens in color and a blue precipitate forms. 



Sections of tissues fixed in alcohol, cut in paraffin, and fastened 

 to the slide by the water method were placed in each of the solu- 

 tions of molybdic acid. From time to time sections were re- 

 moved from the solution, rinsed in water, and tested with a I per 

 cent, solution of phenylhydrazin hydrochloride. It was found 

 that the molybdic acid was taken up by the tissues from both 

 solutions and was detectable in them by the blue reaction obtained 

 by reduction with phenylhydrazin hydrochloride. In sections 

 treated with pure solutions of soluble or of colloidal molybdic 

 acid the strongest reaction was obtained in the collagenic fibrils 

 which were deep blue. A slight diffuse reaction was obtained in 

 the cytoplasm of cells, and a somewhat stronger reaction in the 

 nuclear chromatin. The amount, however, of molybdic acid 

 taken up from dilute pure solutions was not great except as 

 regards the collagenic tissue. The experiments show, however, 

 that molybdic acid may be taken up from its solutions by tissues 

 and may be detected in these by the blue reaction produced by 

 treatment of the sections with phenylhydrazin hydrochloride. 



Under the conditions of the Lilienfeld-Monti-Macallum reaction 

 molybdic acid occurs in the solution associated with nitric acid as 

 well as with ammonium molybdate, ammonium nitrate, and the 

 products of dissociation of all these compounds. Accordingly, 

 the effect of the presence of acids on the absorption of the 

 molybdic acid from its solutions by tissues was tested. Sections 

 were placed in solutions of soluble and of colloidal molybdic acid 

 to which five per cent, of nitric or of hydrochloric acid had been 

 added, and were tested from time to time with phenylhydrazin 

 hydrochloride. I found that the addition of either nitric acid or 

 hydrochloric acid to the solutions of molybdic acid produced a 

 remarkable increase in the capacity of sections for combining 

 molybdic acid, which was again detectable by the blue or green 

 reaction obtained by reduction with phenylhydrazin hydro- 

 chloride. With the mixture of nitric and molybdic acids the 

 reaction obtained after reduction was a deep greenish blue color 

 in the nuclear chromatin, a faint greenish blue in the cytoplasm, 



