addition of ammonium tartrate and a few drops of an alkali; it re- 

 duces silver nitrate at room temperature, and Fehling's solution on 

 boiling. The addition of an alkali soon causes it to take on a dark 

 brown color, lead acetate gives a precipitate, nitroprusside and very 

 dilute ammonia give a wine-red color. All of the above reactions be- 

 ing given also by pyrocatechin, Brunner concluded that Krukenberg 

 was right in his belief that pyrocatechin is present in the suprarenal 

 gland. 



After the discovery of the blood-pressure-raising property of the 

 suprarenal gland, B. Moore,* working in Schafer's laboratory, came 

 to the conclusion that Vulpian's chromogen and the blood-pressure- 

 raising constituent are identical. He based his opinion on the fact that 

 chemical operations which destroy the color reactions by oxidizing the 

 reducing agent appear also to destroy the blood-pressure-rasing con- 

 stituent. That the solubilities of the active principle are the same as 

 those of the reducing agent appears also to support this opinion. 



Fraenkelf worked with residues obtained with the help of alcohol 

 and acetone as solvents. These residues raise the blood pressure and do 

 not contain pyrocatechin, and on the strength of the ferric chloride 

 reaction and its reducing po^ver he concludes that the essential prin- 

 ciple of the residue is a nitrogenous derivative of the or//?odihydroxy- 

 benzene series. 



According to Fraenkel both Krukenberg and Brunner are wrong in 

 their opinion that the suprarenal gland contains pyrocatechin. 

 Fraenkel concludes, like Moore, that the blood-pressure-raising con- 

 stituent and Vulpian's chromogen are one and the same substance. 



More recently still, Miihlmann:|: has attempted to prove that the 

 blood-pressure-raising constituent is a pyrocatechin derivative. He 

 asserts that on boiling fresh suprarenal capsules with dilute hydro- 

 chloric acid the active principle is decomposed and the pyrocatechin 

 which is split off may be taken up with ether. Miihlmann has not, 

 however, furnished conclusive chemical proofs for his assertion. Both 

 Miihlmann and Brunner might have settled this point by precipitating 

 the supposed pyrocatechin with lead acetate and analyzing the lead 

 salt thus obtained. Pyrocatechin may be present in small amounts in 

 the gland, but no proof of this has yet been furnished. 



There is therefore at present great diversity of opinion as to the 



* Journal of Physiology, xvii (1895), Proc. Physiol. Soc, p. xiv. 



f Wiener med. Blatter, 1896, No. 14-16. 



+ Deutsche med. Wochenschr., 1896, No. 26, 409-411. 



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