122 SCIENCE PROGRESS. 



... 



but soluble in dilute acids and alkalis. It is coagulated 

 by contact with alcohol and gives the usual chemical re- 

 actions. 



Besides the stores of proteids thus evidently reserve 

 materials deposited for use after a considerable resting 

 period, we find other stores more immediately available for 

 nutritive purposes. In many plants definite channels in the 

 tissue are stored with a fluid of considerable complexity, 

 known generally as latex. Probably this fluid contains 

 many bodies which are not to be regarded as constructive 

 materials, but rather as in some sense waste products, or 

 at any rate as bye-products of metabolism. Besides these, 

 however, are many plastic substances, such as starch, sugar, 

 etc., and most latex contains considerable quantities of 

 proteids. 



Martin (14) has investigated with great care the latex of 

 the Papau {Carica papaya), working, however, on the dried 

 juice. He has proved that this fluid contains two well- 

 defined albumoses, a globulin and an albumin. To them 

 he attributes the following reactions : — 



Globulin. — Soluble only in solutions of neutral salts, and 



precipitated from such solutions by saturation 



with either sodium chloride or magnesium sul- 

 phate. 



Precipitated from its solutions by large dilution 

 followed by the passing of a stream of CO., through 

 the dilute extract for some time. 



Precipitated by dialysing till the neutral salts are 

 removed. 



Coagulated on heating the solution in 10 per cent. 

 sodium chloride to 70 to 74°C. 



This globulin resembles Weyl's vegetable myosin in 

 most respects, but its coagulation temperature is consider- 

 ably higher. 



Albumin. — Soluble in water and not precipitated by satura- 

 tion with neutral salts. Coagulated in heating and 

 on addition of nitric acid. 



