64 TRANSACTIONS OF THE ILLINOIS 



thought and study have ensued, and progress has doubtless been made 

 in that course of self-education which is constantly going on in the nat- 

 uralistic mind. 



Some of the more prominent positions taken in the papers referred to 

 may be briefly epitomized as follows : 



1. Plants are creatures of habit ; and it is largely to the force of 

 habit that the constancy of form of wild plants is due. 



2. Variations arise when the habit of a plant has been broken up by 

 the application of some new condition of life. 



3. The direction of a variation is determined by influences which 

 have worked upon the parent to call forth new traits necessary to the 

 well-being of the offspring. 



4. Artificial reproduction — that is, propagation in any other way 

 than by seed — is the most positive disturber of the habit of a plant, and 

 will always, sooner or later, result in variations through the seed, and 

 sometimes through the bud. 



5. Hardships in the life of plants, if not too enervating, lead to 

 variations in the offspring, suiting them to withstand such hardships. 



6. Crossing leads to variations — that is, there is not only a mixture 

 of the parental traits, but entirely new traits are apt to appear. 



7. Variations become more and more pronounced the oftener they 

 occur ; the plant, after a time, varying habitually. 



8. It is, to a certain degree, within our power to cause plants to 

 vary in desired directions, so that they may be better adapted to special 

 uses. 



9. Our only hope of improving plants, by introducing new traits, is 

 to act upon the young plant through its parents by making the parents 

 suffer for lack of the traits we desire to have appear. 



ID. Variations by seedlings are more common than by bud, because 

 every seed is a compound product of generation, while every bud is a 

 single generative effort. 



It is my wish, at this time, to consider some of the ways in which 

 variations come about, and, in doing so, to apply the principles just laid 

 down, and see how far they explain observed phenomena, and how far 

 they account for otherwise inexplicable facts. We cannot proceed far in 

 a subject like this, before we find ourselves away back at the source of life, 

 witnesses, as it were, of the very act of creative power which gives every 

 being a beginning of existence. We must study embryology, just as the 

 evolutionists on the one side and the anti-evolutionists on the other side 

 do when they seek to prove their respective positions. Whether the pri- 

 mary form of every living thing, plant or animal, is considered as a simple 

 mass of nitrogenized matter called protoplasm, or whether all live things 

 are supposed to spring from a single cell, called an tgg or ovule, we must 

 all agree that among the forms in which the simple cell, the first principle 

 of plant life, appears, there are but two ways in which it may proceed to 

 become an individual plant. Here, at the threshold of life, there is a 

 fundamental distinction which divides all vegetable individualities into 

 two grand classes. For convenience, let us name these classes "sexual'' 



