226 Cornell Extension Bulletin io 



In that year a very important paper by Gregor Mendel, the Abbot of 

 Brunn, was discovered. Although the paper was published in 1865, 

 the facts were not known nor appreciated during the intervening thirty- 

 five years. Previous to the knowledge of this publication, generalizations 

 only were made as to the result of crosses. Breeders noted that in many 

 cases the offspring was rather intermediate in the first generation, and 

 that later crossings gave some plants like the original parents but mostly 

 of a very heterogeneous nature. Unlike his predecessors, Mendel did 

 not consider plants as a whole, but studied individual characteristics. 

 He illustrated by experiments with the garden pea that there are law 

 and mathematical proportions in the results to be obtained. He first 

 found that crosses between tall varieties and dwarf varieties gave tall 

 forms, but that on propagating from these the tall forms broke up so 

 that seventy-five per cent of the offspring were tall and twenty-five per 

 cent were dwarf. Of the seventy-five per cent tall forms, one-third were 

 pure; the remaining two-thirds were impure and apparently of the same 

 constitution as their hybrid parents. The dwarf forms continued to 

 breed true. Two facts were brought out in this experiment. The first 

 is dominance, or the complete resemblance of the first generation to 

 one parent, the characteristics of the other parent being entirely masked; 

 the second is segregation, or the separating in the second generation into 

 definite proportions of the characters concerned in the cross. Obviously 

 all cases are not so simple. 



As stated by the writer in a previous article (Hottes, 191 5 a), the gladiolus 

 offers an excellent example of a genus of plants that has been improved for 

 garden purposes by the incorporation of a number of species into more 

 complex multiple hybrids than in the case of most garden flowers. The 

 china aster {Callistephus hortensis), the sweet pea (Lathyrus odoratus), 

 the peony {Paeonia albiflora), and the Boston fern {Nephrolepis exaltata 

 var. hostoniensis) have been improved solely by the selection of variations 

 and mutations within a single species. Phlox, German iris, larkspur 

 (Delphinium), dahha, columbine (Aquilegia), begonia, and chrysan- 

 themum varieties have arisen from the hybridization of several species. 

 The rose, the orchid, the pelargonium, and the gladiolus, however, 

 often have in the make-up of their best varieties from three to seven 

 species, each contributing characteristics to the modern degree of 

 perfection. 



It is thus seen that every gladiolus variety dealt with is at the start 

 a multiple hybrid. The variety Princeps is at least a fifth-generation 

 hybrid in which are resident the characters from at least six species. 



