440 R H. A. PLIMMER AND W. M. BAYLISS. 



the above. Until 1893, when Salkowski <4) commenced his experiments, 

 it was supposed that the whole of the phosphorus of caseinogen was 

 contained in the insoluble paranuclein, which was considered by 

 Liebermann to be a compound of albumin with metaphosphoric acid. 

 Only Szontagh, as quoted by Salkowski and Hahn (5) , observed that the 

 paranuclein was further digested, and that phosphoric acid was contained 

 in the filtrate. From Salkowski's own observations and those in con- 

 junction with Hahn, we now know that a great part of the phosphorus 

 of caseinogen passes into solution, and that under the most favourable 

 conditions, such as very fine division of the caseinogen and a great 

 excess of pepsin, the solution may be complete. The presence of 

 phosphoric acid as observed by Szontagh could not be confirmed by 

 Salkowski, who stated that the whole of the phosphorus was contained 

 in a soluble organic compound. About the same time v. Moracze wski (9) 

 also investigated this subject. He found that the whole of the 

 phosphorus never passed into solution, but that a portion was always con- 

 tained in the insoluble paranuclein, which, on further digestion, lost albu- 

 min and became richer in phosphorus. In fact, the amount of this residue 

 depended on the length of time of the digestion and on the dilution. 

 His results were confirmed by Sebelien (2> . The greater the amount 

 of ferment and the greater the dilution, then the greater is the amount 

 of phosphorus which passes into solution. Both these investigators 

 never observed the complete solution of the caseinogen, but always 

 found that there was a small insoluble residue, so that with regard to 

 this point they contradict Salkowski. This small residue has been since 

 shown by Salkowski (6) to be so minute that it is negligible. The net 

 result is, that, under the most favourable conditions of digestion, the 

 whole of the phosphorus of caseinogen passes into solution. Our results 

 do not altogether agree with those of Salkowski, but on the whole they 

 are confirmatory. 



So far as we know, no detailed experiments have been made upon 

 the digestion of caseinogen by papain, this enzyme being supposed to 

 have an action resembling that of pepsin, rather than that of trypsin. 

 By studying its rate of action we have found that it is intermediate in 

 its power of dissolving caseinogen between pepsin and trypsin. For 

 comparison, we have also investigated the action of acid and alkali on 

 caseinogen. One per cent, caustic soda was found to almost exactly 

 resemble trypsin in its rate of separation of the phosphorus, but with 

 regard to the products it was totally different. 



