1907] LAND— EPHEDRA TRIFURCA 2S5 



Ferguson's drawings, which show some of the male nuclei very irregu- 

 lar in outline, suggests the desirability that conclusions as to the 

 equality of irregular nuclei should be based on volume rather than on 

 optical sections. Perhaps the male nuclei of P, Banksiana and P. 

 Laricio are more resistant to the conditions which cause elimination of 

 supernumerary cells than is P. Sirobus. 



In Cupressineae the tendency to mass the archegonia in a common 

 group finds its highest expression; in Thuja the further tendency to 

 eliminate some of the archegonia is also apparent. In this group, 

 with one notable exception, the male nuclei are two, and in all, so far 

 as yet seen, are equal in volume and have equal chances to function. 

 There are good reasons for believing that if few male nuclei were dis- 

 charged into the complex the number of archegonia would be reduced 

 gradually because of failure to function. In most of the Cupressineae 

 the relatively high number of archegonia in a complex seems to be 



■ 



retained by having several pollen tubes reach the complex. 



A member of the Cupressineae gave us the first proof of what 

 seems to have been the primitive condition of the gymnosperm pollen 

 tube. In 1904 JiTEL,'^ studying Cupresstis Goveniana, found some- 

 times four, more frequently eight to ten, and occasionally as many 

 as twenty male cells in each pollen tube. Juel considers the female 

 gametophyte an abnormal one, for in one instance only did it get 

 beyond the free nuclear stage and produce archegonia. The condi- 

 tions which enable these numerous male nuclei to function are cer- 

 tainly ideal. In order to retain the large number of male cells which 

 Juel rightly considers a primitive gymnosperm condition, it seems 

 that for some reason the female gametophyte of Cupressus Goveniana 

 early lost its conservatism and went a step beyond the archegonium 

 complex and formed free eggs. It certainly shows an interesting 

 transition from archegonia to free eggs, and illustrates the tendency 

 among gymnosperms to eliminate archegonia. The massing of 

 archegonia and final elimination of walls must have taken place in 

 Cupressus Goveniana while the male cells were still numerous, for 

 in no other way does it seem possible to preserve the large number of 

 male cells. That Juel did not observe these free nuclei functioning 

 m no way invalidates this conclusion. 



'*5juEL, H. O., Ueber den Pollenschlauch von Cupressus. Flora 93:5^-62. 

 pl.j. 1904, 



