188 



INTRODUCTION TO BOTANY 



the first successful investigator of the mode of inheritance in 

 hybrids, was an Austrian monk, who carried on his researches 

 in his monastery garden for eight years and published his 

 results in 1865. His discovery was little noticed for about 

 thirty-five years, when it quickly became generally known 

 to biologists everywhere. Mendel's law is not quite simple 

 enough to be stated and illustrated in an elementary botany 

 for secondary schools. 1 



177. How hybrids are artificially produced. Hybridizing, or 

 crossing, plants, is sometimes an easy, sometimes a rather diffi- 

 cult, process. It is simplest in unisexual flowers for exam- 

 ple, in those of Indian corn. Here the tassel (fig. 126) is a 



FIG. 161. A few of the many leaf forms of different hybrids between the 

 blackberry and the raspberry 



Modified after photograph by Burbank 



cluster of spikes of staminate flowers, and the ear (fig. 127) 

 is a spike of pistillate flowers, each thread of the silk repre- 

 senting a stigma and style attached to an ovary (grain of 

 corn). In hybridizing corn it is only necessary to tie a paper 

 bag over the ear before the silk appears, in order to keep off 

 stray pollen, and leave it covered until full-grown, then re- 

 move the bag, dust the silk thoroughly with pollen from 

 tassels of the desired crossing variety of corn, and thereafter 

 keep the ear covered until the silk is entirely withered. Some- 

 times in hybridizing corn the stalks are detasseled just before 

 the ears are ready to receive pollen. If all the stalks of one 



1 See R. C. Punnett, Mendelism, The Macmillan Company, New York. 

 Also L. H. Bailey, Plant-Breeding, The Macmillan Company, New York. 



