Vol. X. January, 1906. No. 2 



BIOLOGICAL BULLETIN 



AN EXAMINATION OF THE METHODS FOR THE 

 MICROCHEMICAL DETECTION OF PHOS- 

 PHORUS COMPOUNDS OTHER THAN 

 PHOSPHATES IN THE TISSUES 

 OF ANIMALS AND PLANTS. 



R. R. BENSLEY. 

 (From the Hull Anatomical Laboratory, University of Chicago. ) 



The microchemical reaction for the detection of phosphorus 

 in the tissues of animals and plants introduced in 1898 by Macal- 

 lurn ('98) is a modification of that devised in 1893 by Lilienfeld 

 and Monti ('93). These investigators attempted to demonstrate 

 the distribution of phosphorus in tissues by subjecting the latter 

 for some time to the action of a solution of ammonium molyb- 

 date in nitric acid, after which they were treated with a solution 

 of pyrogallic acid. The nitric molybdate reagent was supposed to 

 liberate the phosphorus from its organic combinations, to convert 

 it into orthophosphoric acid, and finally to precipitate the latter 

 as the yellow phosphomolybdate of ammonium. The further 

 treatment of the tissues with pyrogallic acid had for its object the 

 reduction of the ammonium phosphomolybdate to a lower oxide 

 of molybdenum, which, according to Lilienfeld and Monti had a 

 brown or black color. In this way the pale yellow precipitate 

 containing the phosphorus was converted into a dark-colored pre- 

 cipitate which could be easily studied under the microscope. 



The importance of a microchemical reaction which would ena- 

 ble us to determine accurately the distribution of the compounds 

 of phosphorus not only in the tissues but also in the parts of the 

 cells of the tissues can hardly be overestimated. It is therefore 



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