Al'I'UCATIONN OK KKSULTS OF HK.SKAUCIIKS. 



369 



of the hybrids studied in this research in respect to its 

 macroscopic and microscopic characters, has been found 

 to so differ from its parents that were it not known to 

 be a hybrid there would be ample justification to regard 

 it as a species (see Ipomcea, Pari II). It is well known 

 to the botanist that many of the hybrids included among 

 the hundreds referred to by Pocke are bo individualized 

 as to warrant their assignment as species or Bubspecies. 

 Finally, it seems Erom the present state of our know! 

 edge that the difficulty of hybridization, the tendency 

 to infertility of tl ffspring, the tendency to the develop- 

 ment of characters in the hybrid in excess of parental ex- 

 tremes, a in I the tendency to develop new characters in the 

 hybrid, bear usually an inverse relationship to the near- 

 ness of the parents, while the tendency to intermediate- 

 ness hears usually a direct relationship. Owing, how- 

 ever, to the extreme plasticity of protoplasm the most 

 variable results in hybridization arc to he expected, as 

 is indicated by the results of the studies <>f the starches, 

 as presented particularly in Table II, Parts 1 to '■?(>, and 

 summaries. 



The study of the genesis 0I species is without doubt 

 a study of the evolution of chemical compounds, and 

 essentially of interactions, rearrangements, and com- 

 binations of stereochemic system- and their compon- 

 ents. In the origin of species by hybridization there is, 

 according to the conception stated in the penultimate 

 section, a union of two stereoisomers systems of vary- 

 ing plasticities, female and male, in each of which there 



are assumed to he potentially every or practically every 

 character and character-phase of the parent. More 

 ovi i', this variability of plasticity applies not only to tin; 



.. Sill. ,1- a H hole, I, lit :; 



chemic units. Having extremely complex, plastic, m- 

 teracting -_\ terns, and applying thereto a fundamental 

 knowledge of physical chemistry, especially of organic 



colloids, as is indicated, it eem I tat there should he 

 no more difficulty than in the reaction- ol sub- 



stances generally in reaching satisfactory theoretic un- 

 derstandings of the diverse developmental changes that 

 occur in the hybrid that i<, why some characters are 

 like those of one or the other parent or both paren 

 developed beyond parental extreme-, or new characters 

 appear; or why one parent may he of equal 

 potency in influencing the development of the characters 

 of the hybrid; or why species of remote genera can not 

 be crossed, or, on the other hand, why varieties of the 

 same species may readily be crossed ; or why characters 

 that may have existed in ancestral generations, hut which 

 are not apparent in the parents, may appear in the off- 

 -pnng; or why there may or may not be Mendelian 

 inheritance; or why mutations can he induced arti- 

 ficially by the injection of certain substances into the 

 ovaries, etc., etc. Unfortunately this subject is s 

 that a detailed consideration of such points would take us 

 far beyond the possible limit- of space of this report, and 

 therefore, as previously stated, nothing more can be 

 offered at present than mere suggestions. 



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