Evolution of Vegetal Life. 129 



There were 537 of them ! But one other case will tell the 

 whole story. Darwin counted and estimated the seeds of 

 one of the English orchids — orchis maculata : there were 

 186,000. Taking into account the size of the plant, he found 

 by calculation that if these seeds should all grow, 174,000 

 of them would be sufficient to cover an acre ; that is, in one 

 generation, or one year, the fruit of a single plant would be 

 sufficient to cover an acre ; in two, sufficient to cover the 

 island of Anglesea ; in three to cover 47-50ths, or nearly 

 the whole, of the surface of the earth ! Yet this plant is 

 not increasing in number : not more than one, then, out of 

 186,000 of its seeds, is able to maintain itself to the point 

 of producing other seeds, and carrying on the line. 



Seeing that such is the condition of life, — that all the 

 "soft places" must be taken almost at the moment the 

 doors are opened, and that standing-room only is to be found 

 by the few that are ready to take the places of those that 

 from time to time fall out of the ranks, is it not inevitable 

 that the slightest advantage in any conceivable direction 

 will be favorable, and that the plant having this advantage 

 will be the one that will live and perfect its seed ? 



We have seen that slight variations are the rule in nature. 

 These variations may take any direction. If there are up- 

 on a given space all the tall plants that can there find room, 

 smaller ones only can creep in, and vice versa. If all the 

 material required by complicated organisms is already spok- 

 en for, those only that can live on an inferior quality can 

 find a chance to exist. There are all possible gradations of 

 these conditions. Experience shows that a spot of ground 

 sown with the seeds of several genera of grasses, will pro- 

 duce a greater number of plants, and greater weight of herb- 

 age, than a similar spot sown with a single species. Dar- 

 win found on a piece of turf, three feet by four, which had 

 been left for many years under similar conditions, plants of 

 twenty species, from eighteen genera and eight orders, show- 

 ing a wide difference in character. 



Time will not permit me to even enter upon the details 

 which have been gathered illustrating the nature of this 

 struggle for position, which is incessantly going on, or the 

 evidences of its effect, excepting possibly in a single direc- 

 tion. I should like to explain Darwin's hypothesis of Pan- 

 genesis. I should like to show you how seeds and plants 

 are distributed : borne on the wings of the wind ; carried in 



