42 Mendel's Experiments 



SELECTION OF THE EXPERIMENTAL PLANTS. 



The value and utility of any experiment are determined 

 by the fitness of the material to the purpose for which it is 

 used, and thus in the case before us it cannot be immaterial 

 what plants are subjected to experiment and in what manner 

 such experiments are conducted. 



The selection of the plant group which shall serve for 

 experiments of this kind must be made with all possible 

 care if it be desired to avoid from the outset every risk of 

 questionable results. 



The experimental plants must necessarily- 



1. Possess constant differentiating characters. 



2. The hybrids of such plants must, during the 

 flowering period, be protected from the influence of all 

 foreign pollen, or be easily capable of such protection. 



The hybrids and their offspring should suffer no marked 

 disturbance in their fertility in the successive generations. 



Accidental impregnation by foreign pollen, if it oc- 

 curred during the experiments and were not recognized, 

 would lead to entirely erroneous conclusions. Reduced 

 fertility or entire sterility of certain forms, such as occurs in 

 the offspring of many hybrids, would render the experiments 

 very difficult or entirely frustrate them. In order to dis- 

 cover the relations in which the hybrid forms stand towards 

 each other and also towards their progenitors it appears to 

 be necessary that all members of the series developed in 

 each successive generation should be, without exception, 

 subjected to observation. 



At the very outset special attention was devoted to the 

 Leguminosce on account of their peculiar floral structure. 



