stout: pollinations in CICHORIUM INTYBUS 435 



seed, pollen, roots, and shoots give quite the same precipitations 

 in the sera of animals previously treated with extracts of either 

 shoots or pollen of rye. From these results they conclude that all 

 cells of an individual possess the precipitation properties of the 



species. 



However, there Is some evidence that the general specificity of 

 a species may be modified or limited to some degree by types of 

 isoantlbody reactions (Isopreclpltations, Isoagglutinatlons, Iso- 

 spermatotoxlns, etc.). Also the specificity of the individual Is 

 limited by well-marked cases of organ specificity. These con- 

 siderations certainly suggest that a further refinement of the 

 precipitation method of analysis may reveal still more delicate 

 but nevertheless Important types of Incompatibility in the inter- 

 relations between the cells of such highly specialized organs as 

 pistils and pollen tubes or ova and spermatozoa, and which may 

 be comparable to the cases of so-called autosensltlzatlon. In 

 this respect the appearance of self-sterile plants and animals may 

 perhaps involve the development of some type of acquired im- 

 munity, concerned with the metabolic products of closely related 

 though specifically differentiated tissues. Still It must be admitted 

 that high fertility and vigor, as Burck maintains, Is present in 

 naturally self-fertilized and in cleistogamous forms In which it 

 would seem there would be greatest chance for the development 

 of such immunity. 



It Is especially significant that the prevalent conceptions of 

 the operation of antigen-antibody reactions are based upon the 

 feeding or nutritive activities of the cells. The reactions are 

 assumed to be cellular and, on the whole. Individual. A new- 

 born organism may acquire Immunity or show various types of 

 sensitization through the general property of Its cells to react In 

 much the same way as the parents were able to do. There is at 

 least only an indirect heredity. In that characteristics of the 

 species or race delimit the general range of Its possible variations 

 of Intercellular reactions. 



It Is highly probable that an extension of the knowledge of 

 colloidal relations may decidedly modify the older chemical con- 

 ception of antigen-antibody reactions, at least for precipitation 

 and other closely allied phenomena In which the relative con- 

 centrations of substances Involved are important. In serum 



