STAMENS. 



91 



(fig. 214 ^^). There are forms allied to this last-named plant in which the anthers 

 show very complicated convolutions — like those of the human brain. 



When the time draws near for the pollen to leave its place of origin, its cells 

 — whether in a loose powder or sticking one to another — become free from the 

 inclosing wall of the anther, and lie embedded in the cavity of the pollen-sac, 

 as it were in a purse or pocket, awaiting their release. The pollen-sac, hitherto 



Fig. 216.— Stamens. 



1 Calandrinia compressa. 2 Solanum Lycopersicum. 3 Galanthus nivalis. * Cyclamen europceum. « Ramondia pyrenaiea. 

 6, 1 Cassia lenitiva. 8 Pyrola rotundifolia. 9 Arctostaphylos Uva-ursi. w Arctostaphylos alpina. " Vaccinium 

 uliginosum. 12 Pyrola uniflora. is Medinilla (after Baillon). 1* Vaccinium oxycoccus. is Calceolaria Pavonii. 

 16 Tozzia alpina. i", is Sibbaldia procumbens. is Galeopsis angustifoUa. -0, 21 Erythrma Centaureum. 22^ 23 Melissa 

 officinalis. "\ 25 Calla palustris. 26 Nyctandra (after Baillon). 27, 28 Qlobularia cordifolia. 29, 30 Theobroma Cacao. 

 31 Pinguicula vidgaris. 32 Qarcinia. (All somewhat enlarged.) 



closed, now opens, and the pollen is liberated. This opening or dehiscence of the 

 pollen-sacs is accomplished in various ways. It has been already explained that 

 most young anthers contain four sacs which rarely all remain distinct, but, by 

 the breaking down of the parti-walls between each pair, become merged into 

 two cavities. 



These two cavities may be spoken of as anther-halves. In cases where the 



