THE CLEAVAGE OF PROTEINS WITH ALKALI 113 



either dilute alkali or acid in the cold, but is soluble in 

 alkali on boiling. The clear, aqueous solution of the hapto- 

 phor is alkaline from sodium hydrate held either mechanic- 

 ally or chemically; it is precipitated by mineral acids and 

 by alcohol. It responds to the biuret, xanthoproteic, 

 Millon, and Adamkiewicz tests. Millon's test is not very 

 satisfactory, and in some samples has failed altogether, 

 even after care has been exercised in neutralizing the alkali. 

 It is quite evident that the substance or substances in the 

 protein molecule to which the Millon test is due are for 

 the most part found in the toxophor group. However, 

 the readiness of response to this test varies greatly in the 

 different haptophors. The haptophor substance does not 

 reduce Fehling's solution directly, but does so readily and 

 abundantly after prolonged boiling with dilute hydro- 

 chloric acid. The presence of carbohydrate in the hapto- 

 phor has already been discussed (page 70). Tests with 

 a-naphthol, phloroglucin, and orcin give positive results. 

 Ammonium molybdate gives an organic precipitate, but 

 no evidence of free phosphoric acid. The preliminary tests 

 show the presence of protein, nucleic, and carbohydrate 

 groups. Comparing these results with those obtained in 

 the study of the toxophor, the following statements may 

 be formulated: (1) The toxophor is freely soluble in abso- 

 lute alcohol, the haptophor is insoluble in this menstruum. 

 (2) The toxophor contains no carbohydrate, all of which is 

 found in the haptophor. (3) The toxophor freely responds 

 to the Millon test, while the haptophor does so slightly and 

 in some instances not at all. (4) The toxophor contains no 

 phosphorus, or but little of this element, while the hapto- 

 phor is rich in phosphorus. (5) The toxophor from different 

 proteins seems to be the same, possibly with unrecognizable 

 differences in chemical structure, while the haptophor of 

 each protein differs from that from all other proteins. 



Leach 1 gives the following table showing the percentages 

 of ash, nitrogen, and phosphorus in the haptophor of the 

 colon bacillus: 



1 Loc. cit. 



