258 PLANT-BREEDING 



for the oranges of southern California and many other kinds 

 of fruit-trees, and we may confidently assume that the same 

 rule will prevail for all other trees. 



Among agricultural plants instances of observed cor- 

 relations are very numerous. In potatoes richness of flowers 

 indicates a late ripening of the tubers, an abundance of 

 seed-berries is related to a smaller production of potatoes, 

 and in the same way the extension of the foliage, the number, 

 height and branching of the stems and some other marks 

 may be used in predicting the quaUtics of the harvest. Flax 

 may be judged by its stalks. Long and thick stems, nu- 

 merous side-branches, and numerous pods are assumed to 

 be indicative of strong development and long and solid 

 fibers. In hops the late kinds are richer in resinous sub- 

 stances, but thcii aroma is not so fine as in the earher sorts 

 and the botanical marks of the hop-bells, such as hairiness, 

 length of the axis between the succeeding bracts, and many 

 others may be made use of in judging the value of the differ- 

 ent varieties. Clovers are very rich in elementary species, 

 which may be discerned by the form of the leaves, by the 

 presence or absence of whitish spots on the leaflets, by the 

 size and the color of the seeds and by some other marks, 

 correlated with the practical qualities of the types under 

 consideration. Varieties of vetches (Vicia) in wliich the 

 stems begin to branch at a short distance from the root are 

 less sensible to frosts and bad weather during winter than 

 those which remain unbranched for a longer period. Nu- 

 merous other instances could be given, showing the interest 

 attached to a thorough study of apparently insignificant 

 marks and even of such differentiations as escape the atten- 

 tion of the ordinary observer. 



Instead of prolonging the Hst, however, I prefer to call 

 attention to some cases of especial interest, in which the 

 correlations may be more or less clearly understood. One 



