H. E. Woodman and J. Hammond 1H) 



readily tlirough a filter paper, the filtrate tlieu being almost clear aud 

 possessing the appearance of a protein solutiou. It was slightly viscous, 

 gave a foam on shaking and did not show the amphoteric reaction of 

 fresh milk, but was very faintly alkaline to both litmus and phenol- 

 phthalein. 



A preliminary investigation of the first two samples was carried out 

 as follows. A' small volume of the fluid was diluted with distilled water 

 and one drop of acetic acid was added. On shaking, a white flocculent 

 precipitate settled out in a manner characteristic of the separation of 

 caseinogen from milk by this method. This was filtered off and was 

 shown to be a protein by the usual tests. Furthermore, it answered to 

 all the characteristic tests for caseinogen. (1) It was insoluble in water 

 but dissolved readily in dilute soda and in lime-water aud was rejireciiji- 

 tated by the addition of a drop of acetic acid. (2) When fused with a 

 mi.vture of KgCOg and KNO3, the solution obtained on extracting the 

 residue with water gave a strong phosphate test with nitric acid and 

 ammonium molybdate. (3) The freshly precipitated protein was com- 

 pletely soluble in excess of acetic acid. 



Further tests were made in order to ensure that the substance was 

 not a nucleoprotein, which class of bodies gives most of the general 

 reactions of the phosphoproteins. The presence of nucleoproteins in such 

 a fluid would, moreover, not be at all surprising, especially if it resulted 

 from the filtration of lymph through the walls of the alveoH. That the 

 protein was caseinogen, however, and not a nucleoprotein was shown 

 by: (1) The readiness with which it sjilit off its phosphorus as inorganic 

 phosphate by mild alkahne hydrolysis. Under these conditions, nucleo- 

 proteins do not yield phosphoric acid, the phosphorus remaining bound 

 up in the nucleic acid group (li). (2) The behaviour of the fluid towards 

 rennet. To 5 c.c. of the fluid were added 2 c.c. rennet extract. On placing 

 in a bath at 10°, only a slight turbidity resulted after two minutes. On 

 the further addition of two drops of calcium chloride solution to the 

 mixture, however, the turbidity increased aud a curdy precipitate 

 settled out. A clear mixture of 5 c.c. fluid, 2 c.c. rennet extract and 

 1 c.c. calcium chloride solution was placed in a bath at 40°. In a few 

 seconds, a turbidity spread throughout the hquid, followed by a rapid 

 separation of curdy precipitate. This behaviour was consistent with the 

 presence of caseinogen in the fluid, the rennet producing, in the presence 

 of calcium salts, a precipitate of insoluble calcium caseate from the 

 soluble calcium caseinogate. (3) The absence of any insoluble nuclein 

 residue when the protein was submitted to peptic digestion. 



