136 Shaiv — Structure of the Floivcrs in 



testa. The cells of the outer coat form then a thin zone out- 

 side the indurated one, and bear the hairs which give the seed 

 its silvery appearance. It is noteworthy that, long after the 

 indurated layer has become so heavy that it would seem quite 

 impervious to food, the cells of the outer piliferous layer retain 

 their protoplasmic contents and nuclei, and seem Hke living cells. 

 Meanwhile the aril has formed as a paired proliferation from 

 the primine close to the funiculus and forms spongy masses of 

 highly vacuolated cells. In the mature seed they are seen as. 

 a couple of whitish lobes, rather less than half the length of 

 the seed. The seed is black, 2 j^-3 millimeters in length, and 

 clothed with hair. 



In looking over the structural features it is seen that the 

 aerial cleistogamic flowers show intermediate stages between 

 the other two types alike in form, in position, in develop- 

 ment of sepals, petals, stamens and carpels, and in the minuter 

 details of these, the whole constituting perhaps as neat an 

 illustration as is possible, of the stages whereby a plant 

 reaches a highly modified development. 



Various experiments have been made by cutting off one or 

 another type of inflorescence to ascertain how far growth 

 correlation and compensation might be exhibited. Plants 

 deprived in early July of their evident racemes, developed 

 others from axillary buds. Removing the subterranean clus- 

 ters had no visible effect on the plant and they were not 

 replaced. Subterranean flowers that were exposed turned 

 green within three days. 



The production of the aerial cleistogamic flowers appears to 

 be dependent on the general vigor of the plant, for in one 

 very dry season they were almost wholly lacking. 



POLYGALA PaUCIFOLIA. 



As mentioned above, the only other species of the genus 

 Polygala which bears cleistogamic flowers is P. paucifolia, the 



