434 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



those normally existing in the eggs of another species is, of course, 

 not determined, and their further relation to such isoagglutinins 

 (fertilizin) as Lillie reports is an open question. The results, 

 von Dungern points out, emphasize the obvious fact, which, how- 

 ever, has been somewhat disregarded, that the protoplasm of both 

 sex cells are fundamentally of similar constitution. He further 

 reaches the general conclusion at which I have arrived, that suc- 

 cessful fertilization is not dependent on differences between ova 

 and sperms, but on the similarity of their protoplasmic constitution. 



Studies of precipitation have shown that the introduction of 

 foreign proteins of any kind into the circulation of an animal will 

 lead to the development in that animal of the property of causing 

 precipitation when the serum of such an animal is mixed with clear 

 solutions of the respective protein. Thus far, such studies empha- 

 size the similarity of the proteid metabolic products of the indi- 

 viduals of a strain and have thus been concerned as tests of bio- 

 logical relationship not only of animals but of plants (Magnus 

 and Friedenthal '06, '07a and b\ :\Iagnus '08). 



As far as is now known, isoprecipitins, although present in some 

 animals to some degree, are very irregular in appearance and 

 power. Here, as in agglutination phenomena, there is no known 

 reaction that could account for self-sterility, although it must 

 be considered as possible that refined methods of technique may 

 show similar reactions between the metabolic products of two 

 such organs as pistils and pollen tubes. The so-called "organ 

 specificity" in which antigen antibody reactions depend on organs 

 rather than on genetic relationship may furnish a clue to certain 

 phases of the general problem of sex differentiation and the proc- 

 esses of fertilization especially in highly developed organisms. 

 Here, however, there is a constitutional and chemical similarity 

 in large degree irrespective of anatomical structure quite as in 

 cross-fertility in which specific anatomical identity is not a certain 

 criterion for predicting cross-fertility. That a certain degree of 

 similarity exists in the properties of pollen of different species as 

 well as in the pistils is evident from the results of cultural studies 

 of p(^llen-tuije growth, and it is exident that this is not determined 

 by particular and specific morphological characteristics. 



It should be noted in this connection that Magnus and I-^rieden- 

 thal f'07) haxc presented data showing that in rye the extracts of 



