30 



MORPHOLOGY OP SPERMATOPHYTES 



organ and later became used as a sperm carrier, or whether 

 the reverse is true. It would seem natural to think of the 

 Cyead condition as the more primitive one. 



IV. THE EMBRYO 



The first comparatively full account of the development of 



the embryo is that given by Treub i* for Gycas circinalis, and 



this account has been confirmed by fragmentary observations 



since. The account given by Ikeno ^^ for Cycas revoluta agrees 



Fig. 26. — Oycas circinalis, development of the embryo: A, an ovule from above, show- 

 ing the openings of the necks of several arohegonia, x %\ B, longitudinal section 

 of an archegonium, x 73 ; C, a fertilized egg, showing several free nuclei, x 24 ; 

 D, free nuclei of the proembryo, showing parietal placing, x 36 ; ^, a young pro- 

 embryo, X 15; X a young embryo, showing saclike proembryo, suspensor (fusp), 

 and embryo proper (e), x 6 ; ff, longitudinal section of seed containing two embryos, 

 two thirds natural size; ff, embryo with suspensor, x IJ^; J, a more advanced em- 

 bryo, two thirds natural size ; K, a mature embryo. — After Tkedb (from Engler and 

 Prautl's Nat. Pflanzenfam.). 



in every particular with Treub' s, and fills in certain gaps. 

 There is still almost entirely lacking any knowledge of the devel- 

 opment of the embryo itself. The embryogeny shows three dis- 

 tinct phases as follows (Fig. 26) : 



1. Development of Proembryo. — This name was applied 

 by Treub to the intrasporic development. The oospore en- 

 larges, continuing to receive supplies of nutrition from the adja- 

 cent tissue. The first change observed by Treub was the pres- 



