DIMORPHISM OF THE GAMOBIUM 



437 



and stand out separately from its surface (E). The spores 

 become entangled by their elaters, by the coiling and un- 

 coiling of which they are able to execute slight movements. 



FIG. 113. Reproduction and Development of Equisetum. 



A, distal end of a fertile shoot, showing two leaf-sheaths (/. sh}, and 

 the cone formed of hexagonal sporophylls (sp. pk). (Nat. size.) 



B, diagrammatic vertical section of a portion of the cone, showing the 

 sporophylls (sp. ph) attached by short stalks to the axis of the cone, and 

 bearing sporangia (spg) on their inner surfaces. 



C, a male prothallus bearing three spermaries (spy}. ( x 100. ) 



D, portion of a female prothallus bearing three ovaries (ovy), those to 

 the right and left containing ova, that in the middle a polyplast ; rh t 

 rhizoids. ( x 30. ) 



(A, after Le Maout and Decaisne ; c andD, after Hofmeister.) 



The spores are liberated by the bursting of the sporangia, 

 and germinate, giving rise to prothalli. But instead of the 

 prothalli being all alike in form and size and all monoecious. 



