GROWTH AND SEXUAL GENESIS. 451 



On the average these higher plants are far larger than 

 plants of a lower degree of composition; and on the average 

 their rates of sexual reproduction are far less. Similarly if, 

 among Archegoniates and Phsenogams, we compare the 

 smaller types with the larger, we find them proportionately 

 more prolific. This is not manifest if we simply calculate 

 the number of seeds ripened by an individual in a single 

 season; but it becomes manifest if we take into account the 

 further factor which here complicates the result the age at 

 which sexual genesis commences. The smaller Phaenogams 

 are mostly either annuals, or perennials that die down 

 annually; and seeding as they do annually before their 

 deaths, or the deaths of their reproductive parts, it results 

 that in the course of a year each gives origin to a multitude 

 of potential plants, of which every one may the next year, if 

 preserved, give origin to an equal multitude. Supposing but 

 a hundred offspring to be produced the first year, ten 

 thousand may be produced in the second year, a million in 

 the third, a hundred millions in the fourth. Meanwhile, 

 what has been the possible multiplication of a large Phaeno- 

 gam ? While its small congener has been seeding and dying, 

 and leaving multitudinous progeny to seed and die, it has 

 simply been growing; and may so continue to grow for ten 

 or a dozen years without bearing fruit. Before a Cocoa-nut 

 tree has ripened its first cluster of nuts, the descendants of 

 a wheat plant, supposing them all to survive and multiply, 

 will have become numerous enough to occupy the whole 

 surface of the Earth. So that though, when it begins to 

 bear, a tree may annually shed as many seeds as a herb, yet 

 in consequence of this delay in bearing, its fertility is incom- 

 parably less; and its relatively-small fertility becomes still 

 further reduced where, as in Lodoicea callipyge, the seeds 

 take two years from the date of fertilization to the date of 

 germination. 



340. Some observers state that in certain Protozoa there 



