258 B0TAN7. 



tion of some; (3) the growth of wings or prickles upon 

 the exterior of the fruit; (4) the thickening and formation 

 of a soft and juicy pulp; (5) the hardening of some por- 

 tions of the wall by the development of stony tissue; (6) 

 the thickening and growth of the calyx or receptacle. 



486. In cases where the walls remain, thin and eventu- 

 ally become dry the fruits are said to be dry— e.g., in the 

 bean ; where the walls become thickened and more or less 

 pulpy, they we, fleshy — e.g., the peach. 



487. It is unnecessary here to describe the various kinds 

 of fruits. It is enough to point out that they all appear 

 to have to do with the protection or dispersion of the seeds 

 th'ey contain. Thus the hard walls (as of nuts, achenes, 

 etc. ) or the bitter pulp of some (as of certain berries) are 

 protective, while the sweet pulp (many berries, drupes, 

 etc.) and explosive capsules of others serve to distribute 

 the seeds. 



488. The particular structure of the flower, its position 

 on the plant, and its relation to other flowers in forming 

 flower-clusters of this or that shape, all have reference to 

 pollination (i.e., the placing of the proper pollen upon the 

 stigma). The pollen-cells are dependent for transporta- 

 tion to the stigma upon (1) the wind {anemopJiilous 

 flowers) ; (2) certain contrivances by means of which in- 

 sects (or rarely birds) are made to carry the pollen from 

 anther to stigma (entomophilous flowers) ; (3) the favorable 

 position of the anthers and stigmas, bringing the pollen in 

 the opening anther into contact with the stigmatic surface 

 {autogamous flowers). 



489. The grasses and sedges, and the oaks, beeches, 

 chestnuts, walnuts, birches, and their allies, and a few 

 others, have wind-pollinated flowers, In these the pollen 



