8 HORTICULTURE FOR SCHOOLS 



characters of English history, Gladstone and Tennyson. 

 Darwin's birthday, it will be noticed, is the same as that of 

 Abraham Lincoln. 



11. The origin of species. Darwin was not alone in the 

 discovery of the fact that the forms of plant and animal life 

 are subject to variation; but he studied the matter so pains- 

 takingly, and wrote so convincingly, that his writings have 

 profoundly influenced all scientific thought since his time. 

 His great book, The Origin of Species, was published in 1859. 

 In it he points out that the forms of life are constantly under- 

 going minute changes; that these changes may be so small 

 at the time as to be scarcely perceptible, but that in the course 

 of centuries they become sufficiently great to make the 

 differences recognizable. For example, if a hundred seeds are 

 planted from one parent plant, no two of these seedlings will 

 be alike; and some will be better able to meet the conditions 

 of life than will their fellows. They will tend to persist, and 

 to transmit these differences to their offspring; and the other 

 forms will tend to perish. The process is so slow as to escape 

 observation; but in the course of many centuries the forms 

 of plants and animals will gradually change. This, in essence, 

 is Darwin's theory of evolution by means of natural selection. 

 It is now recognized by scientific men everywhere as one of 

 the fundamental hypotheses to account for the forms of life. 



12. Mendel. Gregor Johann Mendel, an Austrian monk, 

 was born in 1822 and died sixty-two years later. He con- 

 ducted experiments in the crossing of plants, publishing his 

 results in 1865 in a paper under the title "Studies in Plant 

 Hybridization." This paper attracted no attention in the 

 scientific world when it was written, and subsequently re- 

 mained unnoticed until 1900, sixteen years after the author's 

 death. The discoverers of the paper recognized at once that 

 it contained a fundamental law of heredity ; and the researches 

 of the obscure Austrian monk are now known to students of 

 natural science everywhere. 



