THE BOTANICAL WORK OF DARWIN, 
Charles Darwin’s botanical work falls naturally into two 
periods, of which the first ends with the publication of the 
Origin of Species in 1859, while the second begins with the 
appearance of the Fertilization of Orchids in 1862. 
The chronological grouping, however, only holds good to 
a limited extent, and the work can be more accurately 
classified according to its nature and aim. Thus the botanical 
part of the Variation of Animals and Plants is principally 
characteristic work of the first period, though the book 
appeared six years after the Fertilization of Orchids ; but 
here, as in many other instances, the date of publication is no 
guide as to the date of research, and, as a fact, the work in 
question was largely the fruit of earlier years. 
In the first or evolutionary period, plants, like animals, 
were the material on which he tested his ‘ species theory.’ 
In the second period he worked in detail at varied problems 
in plant physiology. 
I believe the classification of his work into evolutionary 
and physiological will be a convenient basis for discussing 
his results, although a somewhat vague line separates the 
classes. Thus, his original interest in the fertilization of 
flowers was purely evolutionary. 4 I was led/ he says, ‘ to 
attend to the cross-fertilization of flowers by the aid of 
insects, from having come to the conclusion, in my specula- 
tions on the origin of species, that crossing played an 
important part in keeping specific forms constant V But he 
continued to study the means of fertilization of Orchids, &c., 
1 Life and Letters, Vol. i, p. 90. 
