312 



MOKPHOLOGY. 



developed entirely inside of the macrosporangiuni, and derives 

 the nutriment for its growth from the cycas plant, which is the 



Macrosporangiuni of Cycas revoluta Roentgen ]ihotoeraph of same, show- 

 ing female protlialTiiun. 



siiorophyte. Archegonia arc developed fn this internal mass of 

 cells. This aids us in deter- 

 mining that it is the prothal- 

 lium. In cycas it is also called 

 endosperm, just as in the 

 pines. 



629. If we cut open one of the 

 mature ovules, we can see the en- 

 dosperm (prothallium) as a whitisli 

 mass of tissue. Immediately sur- 

 rounding it at maturity is a tliin, 

 papery tissue, the remains of tlie 

 nucellus (macrosporangium), and 

 outside of this are the coats of tlie 

 ovule, an outer fleshy one and an 

 inner stony one. 



630. Microspores, or pollen, of 

 cycas. — The cycas pUant illusiraled 

 in the frorilispiece is a female phuil. 

 Male plants al 



center that hear 



lie plants also e,\isl whiell have A sporophyll (stamen) of cycas ; sporangia in 

 small leaves in the center that hear «:;;;■:; ;;;:,:.:;:;^;f\^;^- ' 



i'lg. .■^6g. 

 ii) of C] 



e. /', group of sporangia ; 

 oni Warniinjr.) 



