76 THE VEGETABLE PROTEINS 



when the quantity of salt is so far reduced that the acid compound is 

 no longer soluble therein and the quantity of salt remaining in the 

 solution within the dialyser is sufficient to prevent its re-solution in 

 water. Other so-called seed globulins behave in much the same way, 

 so that, in considering the solubility of globulins in saline solutions, it 

 is important to take accurate account of the quantity of acid present. 



Saturation with sodium chloride was formerly made the basis for a 

 division of the globulins into two groups, myosins and vitellins. This 

 distinction has been applied extensively to the vegetable globulins, and 

 is included, even to this day, in many of the text-books which deal 

 with vegetable proteins. Experience has shown that such a distinction 

 cannot well be made, inasmuch as many of the proteins which have 

 been thus designated as myosins are, in fact, albumins, and some of 

 those which have been designated vitellins are not soluble in saturated 

 sodium chloride solutions. Thus, the so-called myosin in the seeds of 

 the cereals consists entirely of the albumin leucosin, and the globulin 

 of the castor-bean, which is partially precipitated by saturating its 

 solution with sodium chloride, has been found to consist not of two 

 proteins, one of which is soluble in saturated sodium chloride solution 

 and the other insoluble therein, but of one protein which is less soluble 

 in a saturated saline solution than in a more dilute one (326). 



Palladin (368) stated that myosin, i.e., the protein precipitated by 

 saturation with sodium chloride, is a calcium salt of vitellin, and his 

 assertion has been repeated in most of the accounts of vegetable pro- 

 teins that have since appeared. The indirect evidence of this, which 

 Palladin offers, affords no basis for such a conclusion. His further 

 statement that a 10 per cent, sodium chloride solution of vitellin is not 

 precipitated by mercuric chloride, while one made with a dilute salt 

 solution gives with this mercury salt a precipitate which is soluble in 

 a 10 per cent, sodium chloride solution, is easily explained by the di- 

 lution of the vitellin solution with the water in which the mercuric 

 chloride is dissolved. The same quantity of water without the mer- 

 cury salt will give the same precipitate, and if some sodium chloride is 

 added to the mercuric chloride solution no precipitate results. 



While the animal globulins are precipitated by saturating their 

 solutions with magnesium sulphate, many of the vegetable globulins 

 cannot be thus precipitated, but saturation with sodium sulphate, at 

 33, precipitates all of them as yet thus tested. The vegetable globu- 

 lins are precipitated by partial saturation with ammonium sulphate at 

 very different degrees of saturation. Although many of them are pre- 

 cipitated by adding an equal volume of ammonium sulphate to their 



