18 



MORPHOLOGY OF SPBRMATOPHYTBS 



Between the base of the beak and the wall of the embryo sac 

 the nucellar tissue is loose, and at the time of the development 



Fig. 16. — Ovulate sporophylls of various Cyoads : A, Oycas revoluta ; B, Cycas droin- 

 alis ; C, Cycas Nbrmanbyana ; D, Dioon edwle \ E, Bncephalartos Preissii ; F. Zamia 

 inUgrifolia\ G, Ceratozamia Mexicana. — A, after Sachs; C, after F. Voir MtJLLEE; 

 £, after Miquel ; F, after Eiohaed ; JS, D, 6, drawn for Englek and Pkantl's Nat. 

 Pflanzenfam., from which the entire plate is taken. 



of the pollen tubes this whole region of the nueellus disorgan- 

 izes, leaving more or less of a cavity between the pollen chamber 

 and the embryo sac. Into this cavity numerous pollen tubes 

 are often seen dangling from the pollen chamber (Fig. 18), a 





Fig. 17. — Stangeria paradoxa, longitudi- 

 nal section of ovule, x 1 : g, embryo 

 Biio containing endosperm ; s, layer of 

 "sporogenous tissue" around the em- 

 bryo sac; jD, pollen chamber. — After 

 Lang. 



Fig. 18. — Zamia integrifolia\ longitudi- 

 nal section of upper end of nueellus, 

 showing pollen tubes growing down 

 into the archegonial chamber : pt, pol- 

 len tubes ; pc^ pollen chamber ; pg, rem- 

 nant of pollen grain. — After Webber. 



fact especially evident when one lifts off the caplike nucellar 

 beak, which from the disorganization of the tissue beneath be- 

 comes quite loose. 



