DIMORPHISM OF THE GAMOBIUM 



363 



a length of over a centimetre, and produce only ovaries 

 (ovy). Thus although there is no difference in the spores, 



FIG. 85. Reproduction and Development of Equisetum. 



A, distal end of a fertile shoot, showing two leaf-sheaths (/. s/i), and 

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



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

 sporophylls (sp.pk) 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, 

 rhizoids. (X 30.) 



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



the prothalli produced from them are of two distinct kinds, 

 the smaller being exclusively male, the larger female. 



The oosperm develops in much the same way as in 



