CHAPTER XXXII. 



FURTHER STUDIES ON GYMNOSPERMS. 



Cycas. 



428. In such gymnosperms as cycas, illustrated in the front- 

 ispiece, there is a close resemblance to the members of the fern 

 group, especially the ferns themselves. 

 This is at once suggested by the form of 



^ '^^™lji»iAj \ '^^ leaves. The stem is short and thick. 



'^t.i^f*5?)i'. V' The leaves have a stout midrib and 



Lfc^^LiSS'k^y' The leaves have a stout midrib and 



'\fi/i^ t numerous narrovv^ pinnee. In the center 



^*vv! ' iT'" 1 °-^ '^^'^ rosette of leaves are numerous 



T 5^ '1, smaller leaves, closely overlapping like 



^ . ' i ' A bud scales. If we remove one of these 



\^ ai f,. tfW at the time the fruit is forming we see that 



>s' ;|^' ju general it conforms to the plan of the 



» "* ^ large leaves. There are a midrib and a 



j^ jj number of narrow pinnae near the free 



>^j^ end, the entire leaf being covered with 



■^"^ woolly hairs. But at the lower end, in 



1.T '^'u^'ii' ( c place of the pinnae, we see oval bodies. 



Macrosporophyll or Cycas ^ ^ ' 



revoiuta. Thesc are the macrosporangia (ovules) 



of cycas, and correspond to the macrosporangia of selaginella, 

 and the leaf is the macrosporophyll. 



429. Female prothallium of cycas. — In figs. 279, 280 are 

 shown mature ovules, or macrosporangia, of cycas. In 280, which 

 is aroentgen-ray photograph of 279, the oval prothallium can be 

 seen. So in cycas, as in selaginella, the female prothallium is 



214 



