Reactions of certain Synthesized Proteid-like Substances. 345 



not, like them, produce intravascular coagulation when intravenously 

 injected into pigmented rabbits. Neither will the colloid 7 when intro- 

 duced into the circulation of dogs, very slowly and in minute quan- 

 tities, produce a retardation of the coagulation of blood withdrawn 

 from the carotids. 



Colloid c. The colloid B is formed by heating at 125 C. in sealed 

 tubes for three hours, equal weights of para-amidobenzoic acid and 

 phosphorus pentachloride. The resulting product, a grey friable 

 powder, insoluble in cold water, was, after washing to remove the 

 contaminating phosphoric acid, dissolved in concentrated ammonia, 

 and evaporated down at a low temperature in vacuo. The resulting 

 substance appears as a number of translucent yellowish plates, 

 apparently similar to those previously described. They are soluble 

 in warm water, forming an opalescent straw-coloured solution, which 

 is loevorotatory ( D = 42). This solution gives the xantho-proteic 

 and Frohde's reaction, but fails to give the typical colour reactions of 

 proteid-like substances with salts of copper, cobalt, or nickel and 

 caustic potash ; neither does it give the reactions of Millon, Lieber- 

 manii, or Adamkiewicz. It is not precipitated by salicylsulphonic 

 acid, but it is precipitated by salts of the heavy metals. Neutral 

 salts separate it from solution like the preceding substances. When 

 freed from salts, it does not coagulate on heating, but if a trace of 

 sodium chloride or of another neutral salt be present, it coagulates 

 on heating, to 75 C. When intravenously injected into pigmented 

 rabbits, it fails to produce intravascular coagulation, neither does it 

 hasten the coagulability of blood withdrawn from the carotids. It 

 fails to induce a " negative phase " in the coagulation of dogs' blood. 

 This series of results lends additional support to the view that the 

 coagulation of the blood resulting from intravenous injection of the 

 colloid, is due to the interaction of the colloid with the constituents of 

 the plasma, and not to the heavy nature of colloid molecule. 



Colloid e. The colloid c is prepared by heating together equal 

 weights of tyrosine and xan thine with twice their weight of phos- 

 phorus pentachloride at 125 C. for three hours. The product of 

 the reaction is a yellowish powder slightly soluble in warm water. 

 After repeated washing in cold water, it is dissolved in concentrated 

 ammonia, and the resulting solution evaporated down in vacuo at a 

 low temperature. The resulting substance consists of a number of 

 translucent yellowish plates like those previously described. It is 

 readily soluble in warm water, forming a yellowish opalescent solu- 

 tion, which is laevorotatory (a D = 38). 



This solution gives a typical red when heated with Millon's reagent, 

 which is not due to an excess of tyrosine, since the intermediate pro- 

 duct in the preparation of the substance fails to give this reaction. 

 It does not give any other of the distinctive proteid colour reactions, 



2 D 2 



