282 SHULL— GER^IINAL ANALYSIS [April 23, 



Koelreuter, the first hybridologist, started the current in this 

 direction by devoting his attention so strongly as he did to the 

 phenomenon of sterihty in hybrids, which he considered an im- 

 portant test of the specific distinctness of the parents. The very 

 fact of fertihty in the progeny of a cross seemed in later years to 

 terminate its interest for him and only in rare instances in his 

 writings do we find any data as to the characteristics of individuals 

 belonging to second and later generations. 



Gaertner dealt with the subject of hybridization in a much broader 

 way and arrived at many interesting generalizations. However, 

 he also worked almost wholly with species-crosses, purposely choos- 

 ing his material with as wide dififerences as possible in order to 

 facilitate definiteness of descriptions, but in this very effort to gain 

 definiteness, the opportunity for studying the second and later gen- 

 erations was usually lost through the sterility of the first generation 

 hybrids. He did, however, make some studies on such well-known 

 Mendelian material as peas, sweet peas and Indian corn, but only in 

 the last did he study a second generation, and in this the com- 

 plexities introduced by " xenia " were doubtless the chief cause of 

 his failure to find the simple law of segregation. 



Practically all other hybridizers from Gaertner's time on to the 

 beginning of the present century, considered the mere securing of 

 hybrid individuals and their systematic description as the matters 

 of prime value. Thus it was that the combination phenomena of 

 hybridization alone occupied the stage, and the separation of the 

 parental characters and their recombination in different individuals 

 was only imperfectly recognized as variability and returns to one 

 or other of the two parental types. 



Two French investigators, Godron and Naudin, who were work- 

 ing synchronously with ]\Iendel, seem to have come very near 

 sharing Mendel's great discovery, but each of these two investi- 

 gators by a strange chance observed a different phase of the 

 Mendelian phenomena, Godron reaching the conclusion that in 

 mongrels ("metis") all progenies return in several generations to 

 the parental types and then breed true, while Naudin thought he had 

 demonstrated that the progenies continue to vary after the F2 and 



