Polygala polygmna and P. paiicifiora. 131 



ness of the wall at first, and the subsequent great increase in 

 size are clearly shown. When ripe, the microspore has 

 increased to several times its bulk and is nearly spherical. It 

 will be seen that the thickened meridional ridges are at first 

 sunken in inrolled grooves, that later they are pressed out to 

 the level of the spore wall and finally come slightly to project. 

 I am not aware that this increase in size has been noted in 

 other plants. An examination of series of pollens from 

 Hibiscus, Ronddctia, Clerodcndron, etc., showed that the 

 microspores are nearly constant in size after the bud is well 

 formed. 



Andrcccium. — B. The Aerial Cleistogamic Flower. In this 

 the eight stamens typical of the chasmogamic flowers are 

 nearly always represented, part of them in a rudimentary con- 

 dition. The largest of these cleistogamic anthers, however, 

 are smaller than those of the chasmogamic, and contain a less 

 number of microspores (60-120). The superficial cells show 

 quite clearly the stellate thickenings which aid in dehiscence. 

 The microspores are also smaller, in the ratio of about six to 

 seven. A similar increase in size takes place in them, but the 

 range is not quite so great, and the wall always remains thick. 



Andmciuvi. — C. The Subterranean Cleistogamic Flower. 

 In this the stamens are greatly reduced both in size and num- 

 ber. Sometimes only two bear perfect microspores. Rudi- 

 mentary anthers are always found. The number of stamens 

 as well as their development varies, but more than seven seem 

 never to be represented. A well-developed anther may con- 

 tain 40-So microspores. The superficial cell-walls of the 

 anther show only a faint indication of the stellate thickenings 

 so prominent on the surface of the same in the chasmogamic 

 flowers. The microspores are still smaller than in the pre- 

 ceding type, as may be seen in Figure 9, and the wall is 

 relatively very thick. This thickness of the microspore wall 

 in the minute flowers seems quite remarkable, and is the 



