MULTIPLICATION. 87 



variety he wishes to grow, but also because, if any other 

 variety is grown in the neighborhood, its pollen is sure 

 to impregnate his variety and produce a mongrel off- 

 spring. Cross-fertilization then acts in antagonism to 

 the hereditary tendency, and secures variation and not 

 only variation, but more vigorous and robust constitu- 

 tion, and more numerous and more healthy descendants. 

 Self-fertilization, or "in and in breeding," occurs, no 

 doubt, in some instances, especially in cereal grasses ; 

 and there are indeed many cases where, for various rea- 

 sons which need not be cited here, no other mode of fer- 

 tilization is possible. Relative permanence of character 

 is secured by this means, and if constitutional vigor and 

 the health of the offspring be impaired by the long con- 

 tinuance of the process, these ill-effects are provided 

 against by the circumstance that a comparatively trifling 

 change in the flower, or in the circumstances by which 

 it is surrounded, will suffice to prevent self-fertilization 

 and secure cross-fertilization. 



Fertilization of Cereals, It has very generally been 

 stated that the wind is the special agency by means of 

 which the pollen is carried from flower to flower of these 

 plants, and no doubt this is true to some extent and under 

 certain circumstances. From the careful experiments and 

 observations of Mr. A. S. Wilson, recorded in a paper read 

 before the Botanical Society of Edinburgh, Scotland, 

 and printed in the " Gardener's Chronicle," March 14, 

 1874, it appears that self-fertilization is the rule among 

 cereals, though cross-fertilization does occasionally take 

 place and has been effected artificially by various experi- 

 menters. The flowers of wheat, barley, and oats open to 

 a slight degree and allow the anthers to protrude, often 

 quite suddenly ; but whether the flowers fully or but 

 partially open, says Mr. W. , they are fertilized before the 

 anthers are visible outside. " The Belgian farmers," he 



