stout: pollinations in cichorium intybus 445 



ations were grown (illegitimate). These were "healthy and 

 fertile" and "their fertility even increased in the later generations 

 as if they were becoming habituated to illegitimate fertilization" 

 (p. 219). Such evidence shows that variations and fluctuations 

 in self-compatibility and inter-form compatibilities may be so great 

 that highly fertile strains may be derived just as an entire species 

 may be non-dimorphic and either long-styled or short-styled 

 (Scott '65). 



Spontaneous variations involving in marked degree both mor- 

 phological and functional differentiation are seen in the frequent 

 appearance of highly fertile equal-styled strains in several species 

 oi Primula (Scott '65; Darwin '69, '77). 



The rather extended and more recent studies with Primula by 

 Bateson, Gregory, and others have not been directed to such 

 studies as give further light on the different grades of self- and 

 cross-incompatibilities that exist in and between different lines of 

 descent. From the general grouping of their data it appears 

 (Gregory '11, p. 83) that legitimate fertilizations are more fertile 

 than illegitimate fertilization. Gregory further notes that the 

 short style is dominant over the long style, but that in F2 gener- 

 ations from such a cross there are less short-styled plants than 

 would be expected on the Mendelian conception of the integrity 

 of characters as units. He suggests that this may be due to 

 differences in the fertility of various gametic unions, giving real 

 selective fertilization or selective embryo abortion, but he evi- 

 dently recognizes that the degree or grade of fertility between 

 the same types of gametes may differ in different races. In all 

 these studies the relative fertility of pedigreed lines of self-fertilized 

 long-styled or short-styled plants is not indicated, and it is not 

 even clear that such lines were grown in the genetical studies. 



The general behavior of these plants is of special significance 

 in the consideration of whether physiological incompatibility 

 involves too great or too little differentiation, and of the greater 

 problem whether the success of fertilization is most dependent on 

 similarities or dissimilarities. Darwin fully realized that illegiti- 

 mate self- and cross-sterility can best be considered as due to 

 "incompatibilities" that are more functional than morphological, 

 and he even held that in self-fertilization and intra-form fertiliza- 

 tion the incompatibility is in some cases of the same grade, as that 



