CHAP. V. 8AROTHAMNUS SCOPARIUS. 165 



three capsules yielded an average of 4-30 seeds, that is less than 

 half the average number in the four artificially crossed capsules. 

 The ratio of 7 -14 to 2-93, or as 100 to 41, is probably the 

 fairest for the number of seeds per pod, yielded by naturally- 

 crossed and spontaneously self-fertilised flowers. The crossed 

 seeds compared with an equal number of the spontaneously self- 

 fertilised seeds were heavier, in the ratio of 100 to 88. We thus 

 see that besides the mechanical adaptations for cross-fertilisation, 

 the flowers are much more productive with pollen from a 

 distinct plant than with their own pollen. 



Eight pairs of the above crossed and self-fertilised seeds, after 

 they had germinated on sand, were planted (1867) on the 

 opposite sides of two large pots. When several of the seedlings 

 were an inch and a half in height, there was no marked difference 

 between the two lots. But even at this early age the leaves of 

 the selMertilised seedlings were smaller and of not so bright a 

 green as those of the crossed seedlings. The pots were kept in 

 the greenhouse, and as the plants in the following spring (1868) 

 looked unhealthy and had grown but little, they were plunged, 

 still in their pots, into the open ground. The plants all suffered 

 much from the sudden change, especially the self-fertilised, and 

 two of the latter died. The remainder were measured, and I 

 give the measurements in the following table, because I have 

 not seen in any other species so great a difference between the 

 crossed and self-fertilised seedlings at so early an age. 



TABLE LVITL 

 Sarothamnus scoparius (very young plants). 



The six crossed plants here average 2 -91, and the six self- 



