18 MASSACHUSETTS HORTICULTURAL SOCIETY. 



are now claimed to be derived by descent with modification from 

 one or a few germs that were originally vitalized by Creative 

 Power ; but by what agency their development has been produced 

 has not j'et been announced ; all we know is that there has been a 

 constant tendency to produce new varieties ; and that the process 

 of variation by which any great change in organic forms has been 

 effected has been so slow as to be measured only by geological 

 time. Variability, which is the rule among domesticated species, is 

 the exception among the wild, but they become variable under the 

 influences of change of habitat, climate, and food ; and when these 

 changes do take place, new varieties and species more suitable to 

 the new conditions of life than the old, are formed by the conjoint 

 action of self-adaptation and natural selection. Species, although 

 not constant in their characters, are liable to great variations if 

 accumulated through successive generations. Most varieties in a 

 state of nature are local, so that while natural selection is forming 

 a variety suited to the locality it preserves only the individuals 

 adapted to that position, and destroys the rest. Within the limits 

 of a short experience, every species produces its own kind ; but 

 variation may become indefinite in amount, if unlimited time is 

 allowed for the variations to take place. The ways of Nature 

 lead us to suppose that species, like individuals, were developed 

 out of single germs whose parts gradually differentiated one from 

 another. The transformation of matter being a nutritive or 

 vegetable function, primarily is the decomposition by plants of 

 water and carbonic acid, and the formation of organic com^xjunds ; 

 then comes the arrangement of the latter so as to form tissues, 

 which in the simplest construction are cellular ; and this cell 

 formation consists in the separation of the primary structureless 

 germinal matter into consolidated substance which forms the 

 outside of the cell, and the soft almost fluid matter which consti- 

 tutes the cell contents. The organization of a fruit plant then 

 may in part be accounted for by the direct action of external 

 inorganic forces on the organism ; by the organism itself produc- 

 ing self-adaptation, and by natural selection among spontaneous 

 variations, which occurs only when a new individual comes into 

 existence. 



The supposition is quite warrantable that the first traces of fruit 

 plant life existed in the form of protoplastic germs ; that the soft 

 gelatinous matter of the vegetable cell was the agent to which 



