66 THE EVOLUTION OF PLANTS 



sacs in each group), though this is not easily 

 made out when the stamen is mature. Inside 

 each sac a great number of pollen-grains are pro- 

 duced, the sac opening by a slit to let them escape, 

 while the scales of the cone separate a little to 

 give the pollen a free passage into the open air. 

 The whole arrangement is quite different from 

 that in the stamen of an Angiosperm, where there 

 are usually four long pollen-sacs, ranged two 

 and two on each side of the anther; it is more like 

 what we find in Conifers, though in that family 

 the pollen-sacs are nothing like so numerous. 



In describing the female cones, we must first 

 of all leave Cycas out of consideration; what fol- 

 lows refers only to the other eight "genera. 



The scales of the female cone are larger and 

 less numerous than those of the male, but very 

 similar to them in form (see figs. 4 and 5, Mi- 

 crocycas); those of Dioon are the most leaf -like 

 in character. These scales may be called carpels, 

 for they bear the ovules, but, as in the case of 

 the stamens, they have little in common with the 

 corresponding organs of the Flowering Plants. 

 Each carpel regularly bears two ovules, which 

 are seated on the edge of the expanded portion. 

 The ovules are very large, and may grow to the 

 size of a small plum even without being fertilized. 

 (Those of Cycas are still bigger.) The cones, 

 when ripe, are often beautiful objects; in Enceph- 



