THE MALE GAMETOPHYTE 



133 



" prothallial " nucleus. This older view is the one given in 

 ( roebel's Outlines of Classification and Special Morphology. In 

 i vs4 Strasburger 12 recognized the real nature of the two nuclei 

 and interchanged the names, applying them as they have been 

 used ever since. We have substituted the name " tube-nucleus " 

 for "' vegetative nucleus/' not only because the development of 

 the tube is its most conspicuous function, but also because it is 







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Vtts jsafe i\* 



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Fig. 62. — Oypripedium apectabile. Section of microsporangium, showing microspores in 

 various stages of division into tube and generative nuclei; although the divisions 

 are nearly simultaneous throughout the microsporangium, it will he seen that in 

 some cases the nuclei are in the spirein stage, while in others the tube ;ind genera- 

 tive nuclei are easily distinguished ; x 300. 



not the morphological equivalent of the vegetative or prothallial 

 cells of the Gymnosperms and heterosporous Pteridophytes. 



A generative cell is formed by the more or less distinct or- 

 ganization of the cytoplasm about the generative nucleus. This 

 cell usually lies free in the body of the spore, but is often cut 

 off by a distinct wall, as in Typha (Schaffner 31 ), Sparganium 

 ( Campbell 43 ), Naias (Campbell 29 ), Con call aria (Wiegand 45 ), 

 Neottia (Guignard '•'), Populus (Chamberlain 30 ), Asclepias 



