98 THE VEGETABLE PROTEINS 



but, in view of the physiological relations of the toxalbumins and the 

 apparent sensitising power of proteins in the anaphalaxis reaction, it is 

 not improbable that the proteins in these extracts will be ultimately 

 found to be the agglutinating agent. 



D. The Precipitine Reaction. 



The production of precipitines by means of vegetable proteins has 

 been described by Kowarski (207), Jacoby (174), Schutze (461), 

 Bertarelli (30), Osborne, Mendel and Harris (365), Gasis (131) and 

 Relander (394). No special study appears to have been made as to the 

 degree of specificity of the reaction obtained with different vegetable 

 proteins, the preparations used by those who mention this feature of 

 the reaction having consisted of crude products or of vegetable extracts. 

 Obermayer and Pick (296) have made the interesting observation that 

 by iodising proteins the precipitine reaction is lost for the specific pro- 

 tein employed and that the iodised protein produces a precipitine for 

 all other iodised proteins whatever their source, those of animal origin 

 producing reactions with iodised proteins of even vegetable origin. 



E. Biological Relations of Seed Proteins. 



If the chemical and physical properties of the different proteins ob- 

 tained from seeds are compared with one another, it will be noticed that 

 they show many relations which are in harmony with the recognised 

 botanical relations of the seeds from which they were obtained. The 

 most marked instance of this agreement is shown by the protein con- 

 stituents of the seeds of cereals. These contain a relatively large pro- 

 portion of prolamins, which, as we have already stated, are characterised 

 by yielding no lysine and much proline, as well as much glutaminic 

 acid and ammonia and also by yielding relatively little arginine and 

 histidine. The physical properties and general behaviour of all these 

 proteins are much alike and present marked differences from the proteins 

 obtained from other groups of seeds. The proteins from leguminous 

 seeds resemble one another in many respects, but differ noticeably 

 from those of the cereals. The proteins of the pea, horse-bean, lentil 

 and vetch yield preparations of legumin, which have thus far been 

 found to be so nearly alike that no certain distinction can be made 

 between them. The proteins of these seeds, while in the main resembling 

 those from Phaseolus, are not the same, for distinct but slight differences 

 in properties, composition and products of hydrolysis have been estab- 



