89 



stamen of Gnetum it seems to me irrelevant to try to see a 

 homologon between a steril envelop in a female flower of 

 Gnetum and a staminal whirl in a male flower of Welwit- 

 scliia, the more so as in the female flower of Welwitschia not 

 a trace of stamina can be seen. 



It is therefore I think well to limit our criticism to Stras- 

 burger's view; he then considers all of the three envelops of 

 Gnetum to be of equal morphological value. If we keep in 

 mind however that the two outer envelops both contain vas- 

 cular tissue while the inner one never does, it seems to me 

 illogical to take them as to be all of equal value. If I would 

 consider f. i. all three as the homologous of leaves the absence 

 of vascular tissue in the internal one would speak much against 

 my views. 



Now Strasburger considers the outer one to be homologous 

 to the external integument of Ephedra but the latest author 

 on Ephedra Jaccard ^) shows, I think conclusively, that the 

 external envelop of Ephedra is of foliar origin, so that, if this 

 be true, Strasburger's homologon of course is lost. 



I therefore consider with Beccari and Strasburger the female 

 flower of Gnetum as an adventitious bud. This bud first forms 

 two whirls of foliar origin, the outer and median envelop. Ac- 

 cording to this foliar origin of the two outer envelops the 

 external one is first developped: is the eldest. After that the 

 growing point stopped forming foliar organs, and transformed 

 itself directly to an ovule with one integument. This explains 

 why the inner envelop has no vascular tissue, while the two 

 outer ones have. 



Consequently a female complete flower of Gnetum consists of 

 an orthotropous ovule provided with a single integument and 

 surrounded by two whirls of bracts which for convenience's 

 sake I will call internal and external perianth. In the incom- 

 plete flower the inner perianth became rudimentary, a fact 

 which needs not to cause any astonishment. 



1) See historical part. 



