MISSOURI BOTANICAL GARDEN BULLETIN 135 
Gaertner, in the period preceding the publication of the 
“Origin of Species,” experimented extensively in crossing 
different plants, but his work for the most part was not sufh- 
ciently methodical, nor was it carried far enough to discover 
any underlying principle. 
Wichura, in 1865, combined six species of willows into 
One complex hybrid. In France, Naudin, Gordon, and 
Jordan made notable additions to the subject of hybridiza- 
tion, the first-named coming very near to discovering the law 
which is now associated with the name of Mendel. At the 
same time Naegeli was concerned with the hybridization of 
plants in Germany, while Darwin, as is well known, made 
many important contributions, particularly on such subjects 
as the inheritance of the various forms of the primrose and 
other flowers. By the early eighties an immense literature 
on the subject had been accumulated, and the number of 
plants experimented upon constituted a formidable list. In 
spite of this fact, the advance made in so complex a subject 
was comparatively slow, and the greatest differences of - 
| Sees prevailed concerning all questions of hybridization. 
his condition resulted partly from lack of knowledge of the 
essential nature of fertilization and the structure of the germ 
cells which unite to form new individuals, and partly from 
the small number of hybrids usually produced from a cross, 
as well as the insufficient study of the later generations of 
the hybrids. 
Investigators at this time were chiefly concerned with such 
uestions as the degree and cause es sterility in hybrids, 
the relative influence of the male and female parent, whether 
the hybrid was an actual blend of the elements involved, 
or 4 mere mosaic, and similar problems. By this time, how- 
ever, two laws seem to have been pretty well established, 
namely, that in a cross between two pure races or species, 
the hybrids of the first generation were all alike, and 
secondly, that the male and female characteristics produce 
ultimately an equal effect on the offspring. Notwithstand- 
ng the rather general applicability of these conclusions, they 
did not go far enough to make possible the formulation of 
any general laws of hybrid inheritance, and the whole sub- 
ject was more or less confused. 
About 1865, at a time when ee with plant 
hybrids was very active, Mendel, Abbot of Brinn, Austria, 
discovered an illuminating and far-reaching principle which 
since 1900 has been associated with his name. It is a curious 
fact that the significance of Mendel’s experiments with 
garden peas was entirely overlooked by his contemporaries, 
though they are mentioned by Focke as an important con- 
