Introduction 



13 



Fig. 2. Ovary segments of three varieties of gourds (a fruits 

 jaunes, above; poire verte, center; a fruits blancs, below) grafted 

 together. Each variety retains its specific characteristics, although 

 in intimate anatomical and physiological contact with the tissues of 

 other varieties. The portion a fruits blancs must obtain all its 

 nutriment through the tissues of two other varieties, yet remains 

 unaffected by this fact. The dependence of morphogenetic capac- 

 ity on strictly hereditary internal factors is clearly shown. (From 

 Carriere, E. A. 1875. Eev. Horticole 1875 : 14-16, 278.) 



