18 



MORPHOLOGY OF SPERMATOPHYTES 



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

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



FIG. 16. Ovulate sporophylls of various Cycads : A, Cycas revoluta ; B, Cycas circin- 

 alis\ C, Cycas Normanbyana; D,Dioonedule\ E, Encephalartos Preissii \ F. Zamia 

 integrifolia; 6r, Ceratozamia Mexicana. A, after SACHS; C, after F. VON MCLLER; 

 E, after MIQUEL: F, after RICHARD; B, D, G-, drawn for ENGLER and PRANTL'S Nat. 

 Pflanzenfam., from whicli the entire plate is taken. 



of the pollen tubes this whole region of the nucellus 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 7 : <?, embryo 

 sac containing endosperm ; , layer of 

 " sporogenous tissue " around the em- 

 bryo sac; JP, pollen chamber. After 

 LANG. 



FIG. 18. Zamia integrifolia \ longitudi- 

 nal section of upper end of nucellus, 

 showing pollery 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 micellar 

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

 comes quite loose. 



