Extra-Floral Nectaries 



371 



the flower is open and seeking visits 

 from its limited list of select visitors, 

 for cross-pollination. 



But the fact that extra-floral nectaries 

 occur also on some ferns, which have no 

 flowers, indicates most forcibly that 

 the function of these structures is not 

 necessarily to take part in the plant's 

 schemes for avoiding self-fertilization. 



If one must form a general theory 

 covering all cases, it would seem that 

 the most plausible in regard to the 

 extra-floral nectaries is that they have 

 no role of real importance. This idea 

 would have shocked most of the early 

 Darwinians, who would have felt it 

 impossible to account for the origin of 

 the structures, unless through their 

 value to the plant in securing its 

 survival. But most naturalists now 

 agree that there are many structures 

 in every plant and animal which have 

 no conceivable function of real import- 

 ance, and which can hardly have arisen 

 and been maintained because of their 



survival- value. As to how such things 

 originated, we are obliged sometimes 

 to admit that "they just happen;" 

 that there seems to be no particular 

 reason. Once there, they remain; for, 

 if they are of no particular advantage, 

 neither are they of any particular 

 disadvantage. 



It is admittedly dangerous for Man 

 to assume that he can understand all the 

 ways of Nature and decide by his own 

 standards whether or not a certain 

 structure is of value to a plant. But so 

 far as our observation can guide us, it 

 appears that in many cases, at least, 

 extra-floral nectaries must be looked on 

 as little better than accidents in the 

 development of the plant ; they may, of 

 course, have been more useful at some 

 earlier stage in the plant's evolutionary 

 history, but at present we can hardly 

 avoid the conclusion in many cases 

 that they have no vital function and 

 that the plant would probably get along 

 just as well without them. 



Inheritance in Flowers 



Two lines of experiment of strictly genetic interest have been undertake by the 

 Pennsylvania Agricultural Experiment Station — namely, a study of the inheritance 

 of flower form and color in Phlox drummondi, and a similar study in Mirahilis jalapa, 

 the Four O'clock. Both these flowers are among the stock in trade of genetists; 

 the latter is particularly rich in surprises. Correns, for instance, crossing a white 

 with a cream-color, got eleven kinds of red, white, yellow and striped offspring 

 among the grandchildren. In the cross of white and red Four O'clock occurs one 

 of the classic examples of blended inheritance, the color of the hybrid generation 

 being pink, while in most plants the color of one parent dominates in the hybrid 

 generation to such an extent that it completely masks the other. The station is 

 also attempting, in tobacco, to find why hybrids are sterile, particularly in cases 

 where germination is low and where seedlings fail to mature. 



Genetics in New Jersey 



The New Jersey Agricultural Experiment Station, one of the pioneers in plant 

 breeding, has the following projects under way: Inheritance of size and form in 

 tomatoes; inheritance of pungency and of morphological characters in peppers; 

 inheritance in crosses of popcorn with flint, dent and flour varieties, and in hybrid 

 beans and egg plants, the object of the last project being to produce a true spineless 

 commercial kind. A hybrid okra has been developed that may be of value as an 

 ornament. Wide crosses are being made with the Prairie-berry (Solanum nigrum f). 

 An interesting experiment under way is to test the correlation between variability 

 and vigor in a population; while the inheritance of prolificness is being tested in 

 beans, tomatoes, peppers and soy beans, one of the objects being to find out the 

 value of barren plants in any population. 



