17 



of the osseoalbumoid employed in the preceding digestion 

 experiment was treated from time to time with boiling water 

 until no more collagen or gelatin could be present, as indicated 

 by practically complete absence of protein from the washings. 

 The small quantity of osseoalbumoid that remained was 

 filtered off, washed with water and subjected to peptic diges- 

 tion in 1/2 liter of 0.2 per cent. HC1 containing 0.25 gram of 

 pepsin (P. D. & Co. i : 4000) and placed in an incubator at 

 40 C. at 2.25 P.M. 



2.35. No precipitate appeared on heating a filtered sample 

 of the digestive fluid. 



2.50. A precipitate was obtained on heating, which almost 

 completely dissolved on further heating. It reappeared on 

 cooling and was as marked a precipitate as that obtained on 

 the first application of heat. 



The remainder of the peptic mixture, after digesting for 2 

 hours and 10 minutes, was filtered and the hot filtrate treated 

 with (NH 4 ) 2 SO 4 . A flaky precipitate was produced before the 

 solution was completely saturated with (NH 4 ) 2 SO 4 and at a 

 temperature of about 65 C. Most of the precipitate was 

 soluble in water. 



The small amount of undigested matter which was ob- 

 tained after filtering was further digested. To the filtrate, 

 after the digestion of this product for 3 hours, was added 

 (NH 4 ) 2 SO 4 to saturation. 



The substance precipitated by (NH 4 ) 2 SO 4 had the following 

 properties : 



(1) The reaction of its solution was acid (HC1). 



(2) On heating this solution a precipitate was produced 

 which dissolved on further heating and, on cooling, reap- 

 peared. Heated again, the same reactions were obtained, 

 but after a third heating of this solution, the precipitate did not 

 entirely disappear on boiling. 



(3) Duplication with another sample of the treatment 

 just described (2) led to immediate precipitation on heating 

 but boiling did not entirely clarify. On cooling, however, 

 the precipitate was more marked than before. 



