The Various Ways in Which Plants Appeal ii 



cultivated. Is it any wonder, then, that scientific progress is so 

 slow, so laborious, and so expensive? 



There remains one other phase of the relation existing between 

 Science and the mind of Man, which is so fundamental to the 

 subject of this book that we must give it some special attention. 

 It concerns the apparent purposefulness of many biological 

 phenomena, as expressed especially in adaptation. What, then, 

 is this adaptation, with which the writings of Darwin have made 

 us so familiar? It is any feature, whether of structure or action, 

 which brings a life process into harmonious relation with the ex- 

 ternal conditions that affect it. The flatness of a leaf is an adapta- 

 tion to the need for a very wide spread of green tissue to light, 

 as is to be fully explained in the following chapter. The colors, 

 shapes, sizes and peculiarities of form in flowers are chiefly adapta- 

 tions to the utilization of insects in the transfer of pollen, which 

 is an indispensable prerequisite to cross fertilization, as will 

 also be demonstrated in the suitable place. And other cases 

 are known without number, involving not only single features, 

 but often the cooperation of several. Now the question is this, — 

 in what way has this remarkable fitness of form to function, of 

 structure to use, of parts to environments arisen? It was form- 

 erly supposed that these adaptations were the direct work of the 

 Creator, — the eternal, immeasurable, omniscient, and om- 

 nipotent, — as Linnaeus grandly characterizes him in the Systema 

 Naturoe. But Darwin gave evidence, in The Origin of Species, 

 greatest of all secular books, tending to show that they arose 

 by a gradual process of evolution, developing in causative touch 

 at every step with the conditions which they fit; and this view 

 has long appealed as satisfactory to most biologists. But in 

 our own day it is becoming somewhat customary to attribute 

 adaptations rather to various adventitious origins, and to explain 

 their persistence merely by the negative supposition that they 

 are not out of harmony with the conditions concerned. In a book 

 of this kind it is needful to take a definite position on this subject, 



