354: i'LA^;T STUDIES 



the iiitni-semiiKil devdopnent. In this condition the em- 

 bryo mil}' continnu for a very long time, and it is a ques- 

 tion wliether it is death or suspended animation. Is a 

 seed alive ? is not an easy question to answer, for it may 

 be kept in a dried-ont condition for years, and then when 

 placed in suitalde cunditions awaken and put forth a liv- 

 ing plant. 



Tliis " awakening " of the seed is spoken of as its " ger- 

 mination,"' hut this must not be confused with the germi- 

 nation of a spore, which is real germination. In the case 

 of the seed an oos])ore has germinated and formed an em- 

 bryo, which stops growing for a time, and then resumes it. 

 This resumption of growth is not germination, but is what 

 happens when a seed is said to " germinate." This second 

 jieriod of development is knowji as the cxI fd-xcminii]^ for it 

 is inaugurated by tlie escape of the spoi'ophyte from the 

 seed coats (Fig. '.\\~i). 



%\\. The great groups of Gymnosperms. — Then? are at 

 least four living gi'oups of (lymnospernis, and two oi' three 

 extinct ones. The groups dilfer so widely from one an- 

 other in luiliit as to show that Gymnosperms can Ije very 

 much divci'sified. They arc all woody forms, Init they may 

 be trailing or straggling shrubs, gigantic trees, or high- 

 climbing vines; and their leaves may be needle-like, broad, 

 or " feni-like." For our pui'pose it will be only necessary 

 to dettne tlie two most prominent gr(iU})S. 



2:'>5. Cycads. — C'ycads a.re ti-opical. Fern-like forms, with 

 largo branched (compound) leaves. 'I'lic stem is either a 

 coluunia.r shaft crowned with a. rosette of gi'cat briinching 

 leaves, witli tlie general habit of tree-ferns and jialnis (Figs. 

 ICi, :il()); or tlicy are like gi'eat tubers, crownt'd in the 

 same wary. In ancient tinu's (the Mesozoic) thev wei'e very 

 abund.'iid, forming a cons]iicuous fcatui'c of tlu' vegeta- 

 tion, but. noM' tbc\' are I'epi'cscnl ed (iiil\- bv about eiglitv 

 forms sc;itlere(l through belli (tie oriental and iiccidcntal 

 tropics. 



