12 INTRODUCTORY REMARKS. CHAP. L 



the seeds. Sometimes a few would germinate on one 

 side before any on the other, and these were thrown 

 away. But as often as a pair germinated at the same 

 time, they were planted on opposite sides of a pot, with 

 a superficial partition between the two; and I thus 

 proceeded until from half-a-dozen to a score or more 

 seedlings of exactly the same age were planted on 

 the opposite sides of several pots. If one of the young 

 seedlings became sickly or was in any way injured, 

 it was pulled up and thrown away, as well as its 

 antagonist on the opposite side of the same pot. 



As a large number of seeds were placed on. the sand 

 to germinate, many remained after the pairs had been 

 selected, some of which were in a state of germination 

 and others not so ; and these were sown crowded 

 together on the opposite sides of one or two rather 

 larger pots, or sometimes in two long rows out of doors. 

 In these cases there was the most severe struggle for 

 life among the crossed seedlings on one side of the 

 pot, and the self-fertilised seedlings on the other side, 

 and between the two lots which grew in competition 

 in the same pot. A vast number soon perished, 

 and the tallest of the survivors on both sides when 

 fully grown were measured. Plants treated in this 

 manner, were subjected to nearly the same conditions 

 as those growing in a state of nature, which have to 

 struggle to maturity in the midst of a host of 

 competitors. 



On other occasions, from the want of time, the seeds, 

 instead of being allowed to germinate on damp sand, 

 were sown on the opposite sides of pots, and the fully 

 grown plants measured. But this plan is less accurate, 

 as the seeds sometimes germinated more quickly on 

 one side than on the other. It was however necessary 

 to act in this manner with some few species, as certain 



