Gladiolus vStudies — II 229 



variety in mind, and then choose parents having characters, that being combined, 

 should tend to produce this ideal result. These parents are then crossed. . . . 



The cross-bred seeds thus produced are sown. . . . 



. . . These hybrids must be self-fertilized, and it is important to lay stress on 

 the necessity of sowing a large amount of seed from which your family of the second 

 generation is to be grown. There must be enough to give a chance for the combination 

 of your desired qualities, and the possibility of other rarer combinations to appear 

 in order to obtain novelties. 



Fischer has noted dominance and the recombination of preexisting 

 characters. For example, " in crossing a large red flower with a small 

 white one, the offspring all came in different shades of red in the first 

 generation, and all were large sized flowers; in the second generation 

 the majority again came red, but a few came light colored and white 

 with large sized flowers." 



Growers have noted that the colors in certain varieties change, due 

 to an external influence of various heat, moisture, or soil conditions. It is 

 known that when the hydrangea flower is given a treatment of iron it 

 becomes a clear blue; and the red flower of Primula sinensis var. rubra, 

 when grown in a temperature of from 15° to 20° C., yields white flowers, 

 while it wnll again produce its red flowers under normal conditions. 

 Obviously, the variety alba, which has white flowers, produces them 

 at any temperature. When a transplanted variety is again grown in 

 its original locality, the old characters should return. Growers who have 

 contended that there are various types of certain varieties due to the 

 locality in which they are gro^\Ti, can easily determine whether or not 

 these varieties are identical b}^ growing all of them on trial grounds for 

 several years and observing whether they resume their normal or identical 

 appearance. If not, the varieties are different. 



It must not be forgotten that, as J. A. S. Watson (19 12) suggests, for 

 the breeder of plants the environment is of first-rate importance, for it often 

 sets a very definite limit to what he can accomplish. Our better varieties 

 of apples and carnations can reach their full perfection only under closely 

 regulated conditions; and improvement is frequently made possible only 

 when we find means of improving the environment. Nurture, in the 

 wide sense, must remain a matter of extreme importance for the race, 

 even if, as seems likely, its effects pass awaj^ with individual life. 



Weismann, the great German biologist, has given the basis for this 

 belief in the non-inheritance of acquired characters, in pointing out the 

 fact that germ and body plasm are quite separate, the germ plasm depend- 

 ing on the body plasm only for its nurture. The body plasm responds 

 quickly to external changes, but this tissue is but temporary and lives 

 for one generation only, while the germ plasm is carried over from one 

 generation to the next. Characters to be inherited must be impressed upon 

 the germ plasm. At present no way is knowTi by which the body cells 

 can influence the germ cells other than by transfer of food. 



