32 



Mr. J. R. Green. 



[Jan. 14, 



peptone is concerned, and shows that by the process peptones and 

 albmnoses may be separated. A recent paper by Kuhne* also dis- 

 cusses this question, and shows that true peptone remains in solution 

 while the ammonium sulphate throws down all the albumoses. He 

 further explains the results that Heynsius arrived at, by showing 

 that the commercial specimens of peptones that the latter used and 

 thought to be pure were largely mixed with albumoses. Though 

 peptone has not yet been precipitated by saturation of its solution 

 with neutral salts, it seems to be almost the only form of proteid that 

 has refused to behave so, and it seems to be rather a question of what 

 salt will throw down a particular proteid, than that such precipitation 

 is a mark of any particular group. 



The solution of the alcohol precipitate differed also from that of an 

 animal peptone, in not giving a pink colour on the addition of sodic 

 hydrate and a drop of cupric sulphate (biuret reaction). It agreed 

 with it, however, in not giving a precipitate with potassic ferro- 

 cyanide and acetic acid. 



Careful investigation of this body disproved the idea that it might 

 really consist of a mixture of an albumose and a peptone for the 

 solution of the precipitate, whether prepared by saturation with 

 neutral salt, or by treatment with excess of alcohol, uniformly 

 answered all the tests applied as described above. The dialysate also 

 behaved on all these points just as the solution before dialysis. 

 There is no doubt, therefore, that the body was a single one and not a 

 mixture. 



In examining the proteids found in other plants this body was again 

 met with, and its reactions investigated at some length. It will be 

 convenient therefore to postpone summarising them until later. 



A little later in the year Mr. Dyer kindly sent me a bottle of the 

 latex of Mimusops globosa, Ga3rtu (Sajpotacece).^ This differed very 

 much from that of the East Indian latex-yielding trees, being a thick, 

 almost pasty, liquid of white appearance and sour smell. It would 

 not filter clear through paper and was therefore submitted to the 

 action of the filter-pump used before. The diluted filtrate, and a 

 watery extract of the dried residue, were taken for examination. 



The solution thus obtained proved on investigation to contain two 

 proteid bodies, which could be separated from each other with 

 tolerable ease. On heating the solution gradually, having first 

 neutralised, a little opalescence appeared, but it did not become par- 

 ticulate even at the boiling point. When the liquid was made either 



* "Albumen und Peptone," " Yerliand. d. ]STaturhist.-Med. Ver.," Heidelberg, 

 N. I\, Bd. iii, H. 4, 1885, s. 286. 



f [The well-known source of the Gum Balata of British Gruiana, from which the 

 specimen was obtained. The specimens were kindly procured by Mr. Gr. S. Jenman, 

 Superintendent of the Botanic Grarden, British Gruiana. — W. T. T. D.] 



