88 THE VEGETABLE PROTEINS 



sufficiently purified, by repeated precipitation, they are obtained wholly 

 free from this substance. A careful examination of well-purified pre- 

 parations of nearly all the known seed proteins has shown that these 

 can easily be obtained by reprecipitation entirely free from phosphorus, 

 and there is no ground whatever for believing phosphorus to be a con- 

 stituent of their molecules. The vitellin of the egg yolk under these 

 conditions retains its phosphorus completely and in this respect differs 

 in a marked degree from edestin. No evidence has as yet been ob- 

 tained that phosphoproteins occur in plants, and in view of what is now 

 known it seems probable that these occur in very small quantity if 

 they occur at all. 



(d) Hcemoglobins. 



Whether proteins which resemble haemoglobins are to be found in 

 plants is still an open question, although the coloured crystals of 

 phycoerythrin and phycocyan which Molisch (277, 278) obtained 

 from some of the sea algae appear to be similar in many respects to 

 haemoglobin. 



(e) Lecithoproteins. 



Lecithoproteins have not been isolated from plants, and satisfactory 

 evidence of their existence has not yet been brought forward. Schulze 

 and Likiernik (496) and Schulze and Winterstein (506) assume the 

 presence of lecithalbumin in seeds from the fact that a part of the 

 lecithin always remains undissolved when the powdered seeds are ex- 

 tracted with ether. 



Hoppe-Seyler (167), as just stated on page 87, obtained a lecithin- 

 like substance from crude preparations of the proteins of the Brazil-nut 

 and pea, but his brief statement is not sufficient to warrant the conclu- 

 sion that this lecithin was anything other than a contamination of the 

 preparations which he examined. 



III. DERIVED PROTEINS. 



I. PRIMARY PROTEIN DERIVATIVES. 



The members of the various groups of derived proteins are all re- 

 presented by corresponding products obtained from vegetable proteins. 

 As these have been discussed in Chapter VII. in connection with the 

 denaturing of these proteins they require no further mention here. 



