CYr'ADALRS 



15 



of Cycads is "worthy of note. In the parks of Chicago we ob- 

 tained a stroliihis of Dioon eduJe which measured 30 centime- 

 ters in height and 20 centimeters in diameter ; and one of Cycas 

 rerolula which measured 50 cen- 

 timeters in height, and a1)ont 

 tlie same in diameter. 



In Cyi'iis tlie sporophyils re- 

 semlile tlie foliage leaves in gen- 

 eral form (Fig. 14), the stroljilns 

 appearing as a rosette of nuich 

 smaller and yellowish leaves. 

 An interesting transition may 

 be traced from the leaflike spo- 

 rophyll of Cycas revoluta tn 

 such specialized ones as those nf 

 ZtDiua or C'eiritozamia (Figs. 

 14, 15, 10). In the sporopliylls 

 of Cyrus rei'oluia the upper 

 pinnaj are prominent, bnt the 

 lowest ones, usually three on 

 each side, are replaced by s])o- 

 rangia. In Cycas cirriudlis the 

 upper sterile pinnte are unich re- 

 duced; while in Cycas A^ormaii- 

 hyaiia the terminal portion of 



the sporophyll is merely toothed, the lowest pair of teeth being 

 replaced by sporangia. In Dioou, and Encephalai'tos the sterile 

 portion is still leaflike, bnt it is entire, and ii pair (jf sporangia 

 occu]")y a basal position; while in Zanila and Ceratozainia the 

 sterile tip has become a peltate expansion, and beneath it is 

 the pair of sporangia. 



Investigations in reference to the develnjiment of the mega- 

 sporangium have been incidental to a study of the embryo sac 

 structures. Important among these contributions liave been 

 those of Warming «• » on Cyras in 1877 and 1871) ; of Treub "' ^^ 

 on Cerafozamia and Zainla in 1881 and 1884; and most recently 

 of Lang-'' on ^tangeria paraclo.ra. The authors have also had 

 the privilege of looking over nniterial of Zamia kindly supplied 

 by llr. II. J. AVebber. From these accounts, and from per- 

 sonal (jbservation, the general facts seem to lie as follows: 



G. i-I.— fliiMii .'./«/.-, ovulate strcljil 

 us ; yurfaec view : ■ y.^ — Frmii plio 

 toirrapli taken iu T/nii'olu I'ark. tjlii 



