694 SCIENCE PROGRESS 



per cent. For its preparation the seeds are extracted with water 

 or dilute salt solutions, the whole of the dissolved proteins 

 precipitated by saturation with ammonium sulphate, and a 

 solution of the precipitate subjected in dialysis. The globulins 

 become insoluble with the removal of the salt, and from the 

 remaining aqueous solution leucosin may be precipitated in the 

 usual wa3\ It is coagulated at a temperature of 52° ; this is 

 lower than the heat-coagulating point of the corresponding 

 animal albumins. It contains 16 per cent. N. and 1*5 per cent. S. 

 and on hydrol3'sis it furnishes nearly four times as much mono- 

 amino-N as diamino-N. 



2. T/ie Phyto-globitlins. — The best-known vegetable proteins 

 belong to this class, and the}^ represent the main reserve pro- 

 teins of the seeds. Their properties are so much like those 

 of the animal proteins that they have been considered by 

 Chittenden and Osborne — to whom we are mainl}^ indebted for 

 our knowledge about them — as directly analogous to the animal 

 globulins. The ease with which man}^ of them assume a crystal- 

 line form, however, distinguishes them from the animal globulins. 

 It is true that lately a doubt has been expressed by Wiman as 

 to their globulin character, as he found 0*4 per cent, phosphorus 

 in legumin, the globulin of peas. But Osborne upholds his view 

 that the purified substances must be considered as phosphorus- 

 free real globulins. Only phosphorus-free proteins ought to be 

 included in this class. 



The best-known representative of this class, and one which, 

 on account of its easy preparation, has been most thoroughly 

 examined, is cdcstin. It seemed from their properties and com- 

 position that the various crystallised globulins called edestin, 

 and obtained from the seeds of wheat, oat, maize, sunflower, 

 cucumber, cotton, flax, and hemp, represent all one and the same 

 substance. But the anal3'sis b}' Hausmann's method, carried 

 out by Osborne and Harris, revealed distinct differences in their 

 molecular constitution. Edestin is easily prepared in large 

 quantities from hemp-seed, which contains about 6 — 8 per cent, 

 edestin. The seeds are first treated with benzene, to remove 

 the oil, then extracted with 5 per cent, salt solution at 60° C, and 

 filtered warm. On cooling, edestin crystallises out, and may 

 be easily recrystallised in the same way. It usuallj^ forms 

 well-defined octahedra, but on slow crystallisation prismatic 

 cr^'stals may be obtained. Its insolubility in water distinguishes 



