286 BOTANICAL GAZETTE [October 



-' In this connection it may be well to call attention to Microcycas calo- 

 coma J recently studied by Caldwell, ^^ which shares with Cupressus 

 Goveniana the distinction of having retained a large number of 

 spermS; sixteen being discharged from a single pollen tube. Large 

 numbers of clustered archegonia are scattered all over the female 

 gametophyte ; also in numerous cases multinucleate archegonia 

 were noted. This last condition seems to show that Microcycas 

 while retaining archegonia has also only partially established septation 

 among the free nuclei. The writer believes that the multinucleate 

 archegonia of Microcycas are homologous with the ^'archegonial 

 tubes" of Tumboa, and that the female gametophyte instead of being, 

 as Caldwell believes, the most primitive in cycads, has attained 

 almost if not quite to the level of Tumboa. The same tendency to 

 eliminate archegonia that is shown in all other groups of gymnosperms 

 holds for cycads in a marked degree. 



The Gnetales present practically an unbroken series illustrating 

 the disappearance of archegonia and the coming-in of the embryo sac. 

 In E. trijurca the long-necked/ slightly scattered archegonia are very 

 similar to those of Podocarpus. The antipodal end of the gameto- 

 phyte is strikingly like the same region of Torreya, but the micropylar 

 end shows an advance over Torreya in having the cells more loosely 

 arranged and the jacket cells sometimes simulating eggs. The per- 

 sistence of two equal male nuclei is perhaps due to the fact that the 

 nuclei of the jacket cells in most cases become free. Another taxad 

 character of Ephedra is the absence of resin ducts. It must not be 

 assumed because of these resemblances to taxads that Ephedra, and 

 of course the other Gnetales, are an offshoot from the Taxaceae. 



A comparison of the female gametophyte of Tumboa shows a 

 close resemblance to that of Ephedra in the antipodal region, but the 

 micropylar end shows a very decided advance. Pearson (/. c.)^n^^ that 

 the "corpuscula" described by Strasburger and by him considered 

 as archegonium initials are in reality multinucleate. He calls them 

 "prothallial tubes" and considers the micropylar region as even more 

 highly specialized than in Gnetuih. The evidence obtained from a 

 study of the tendencies of the female gametophyte of all groups of 



17 Caldwell, O. W., Microcycas calocoma. Box. Gazette 44:ii8-i4i* P^^- 

 10-13. 1907. 



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