Bionomics. 191 



(3) The environment seems sometimes to give the 

 organism what may be called a variation-stimulus. An 

 environmental change may "let loose" a constitutional, 

 congenital, or germinal predisposition to vary in a given 

 direction, or it may stimulate germ-plasm to vary in 

 some new way, the result being manifest in the next 

 generation. 



(4) Environmental changes (topographical, climatic, 

 &c.) impose or remove restrictions on distribution and 

 on the range of possible pairing among the members 

 of a species. In other words, the relations of organisms 

 and their environment include isolation and dispersal. 



(5) There is the relation of elimination, wherein the 

 environment operates unequally on the members of a 

 species, killing some and sparing others, shortening the 

 life of some and lengthening that of others, inhibiting 

 the reproduction of some and favouring that of others, 

 which is one aspect of the struggle for existence. 



Perhaps the most far-reaching word in biology is 

 this word adaptation or fitness. The idea it expresses is 

 familiar to all. Everyone knows of associ- 



,, , ^ r - . ... Adaptations. 



ations of men whether firms or societies, 

 universities or families in which the component mem- 

 bers pull well together, and are, or become, mutually 

 adapted. Similarly with plants and animals; there is 

 internal adaptation of organ to organ, as of bone to 

 muscle; there are adaptations of the organism to its 

 inanimate surroundings, as the cactus to the desert; 

 there are adaptations of organism to organism, as the 

 flower to its favoured insect-visitors, and the insects to 

 their favourite flowers. The study of bionomics is in 

 great part concerned with these adaptations. 



In discussing sex and reproduction in plants, we 

 have briefly noticed the pioneer work of Sprengel 

 Christian Konrad Sprengel (1750-1816), but 

 he cannot be left out of a chapter on bionomics. 



After being ejected from the rectorate of Spandau for 

 neglecting his flock in favour of flowers, he settled 

 down to a frugal life in Berlin, and gave lessons in 

 languages and botany. A back room at the top of a 

 lodging-house was filled with his herbarium, his books, 



