PROTEIN REGENERATION 31 



ever, of Levene and Van Slyke (252, 253) would incline one to 

 the view that the substance belonged more to the proteose than the 

 true protein group of bodies. Levene and Van Slyke carried out a com- 

 plete hydrolysis of the material, with subsequent isolation of the amino 

 acids, and found that it contained at least thirteen amino acids. It 

 must, therefore, be regarded as a fairly complex body. The evidence 

 (253) obtained by the investigation of the viscosity also pointed rather 

 to its proteose than its protein nature, precipitation taking place 

 owing to mere difficulties of solution, as Sacharoff had already sug- 

 gested. 



Synthesis in the Gastric and Intestinal Mucous Membranes. 



Closely allied to this work on plastein formation is that of Hofmeis- 

 ter and his pupil Glaessner some of whose observations were made 

 previous to the publication of the work of Danilevsky and Okuneff. 

 Hofmeister (197) stated that if proteoses were left in contact with the 

 gastric mucous membrane they were converted into protein. In his 

 experiments he divided the stomach of a dog, which had been killed 

 at the height of digestion, into two approximately equal parts. One 

 of these parts he immersed at once in boiling water, and the other 

 he placed for two hours in an incubator. He then estimated the 

 amount of proteose and peptone obtainable from each part employing 

 the biuret reaction colorimetrically for the purpose. A diminution, 

 even a complete disappearance, of proteose and peptone, was observed 

 in the incubated half. He concluded therefore that the proteose and 

 peptone had been converted into protein through the agency of the 

 gastric mucous membrane. He found that, if he had previously 

 warmed the part of the stomach to be incubated to 60 for a short period, 

 it lost its synthetic power. Glaessner (154) confirmed these experi- 

 ments of Hofmeister using, however, more exact methods. He killed 

 dogs three to fourteen hours after a heavy meat meal, and immediately 

 removed the stomach, which he carefully freed from its contents, then 

 divided into two approximately equal parts. In one part the pro- 

 teose content was at once determined whilst the other part was placed 

 in a moist chamber at 40. He found, like Hofmeister, that there 

 was a very marked diminution in the amount of proteose to be ob- 

 tained from the incubated part and at the same time no increase in 

 lower digest products. He also concluded that a true resynthesis of 

 the proteose to protein had taken place a synthesis which began 



