10 The K volution of Fruits. 



which seedHngs can hardly flourish. It is to secure the 

 dispersion of the seed that fruits become attractive to 



birds. 



In the insertion of foliar organs the spiral arrangement is 

 far more general and in all probability earlier than the 

 whorled : the multiplication of similar parts is a rudimentary 

 character throughout organic nature, as exemphfied in the 

 somites of a centipede or the tail-vertebme of Arclmopteryx ; 

 every probability of comparative anatomy points to the 

 earliest carpels as being as leaf-like as those of a pea, or of 

 the bladder-senna [Colutea], and to the ovules as being several 

 in number in each of the distinct carpellary ovarian chambers. 

 In other words, we have as our primitive fruit a spiral of 

 follicles, as in Magnolia. 



That from such a starting-point such infinitely various 

 forms should have resulted may perhaps be partly explained 

 by the abundant supply of available nutriment determined 

 towards the ovary by the act of impregnation, as towards a 

 leaf or shoot by the virus of a gall-fly. 



Keproductive structures being produced under influences 

 diametrically opposed to those stimulating vegetative growth, 

 there is a general tendency to truncation of the floral axis, 

 the alternate phyllotaxis thus producing an arrangement of 

 the floral organs in whorls of five or three — an arrangement 

 soon inherited congenitally. 



The crowding of the organs towards the centre of a 

 flattened floral receptacle tends to reduce the number of 

 carpels compared to that of the sepals, petals, and stamens; 

 and similarly the crowding within the ovary tends to produce 

 the abortion and reduction in the number of ovules. Nor is 

 this mechanical result disadvantageous. It allows of the 

 larger growth of the seed, ^. e., the accumulation of a more 

 abundant food-supply, rendering the seedling longer inde- 

 pendent of the atmosphere. Most small annuals, which are 

 exposed to great risk of individual extermination, produce 

 numerous small seeds ; but, as large and highly-organised 

 animals, such as the elephant, produce few ofispring, so trees 

 which exist longer individually do not require many seeds in 



