XXX 



REDUCTION OF THE GAMOBIUM 



369 



that the two cells in which the sperms are developed repre- 

 sent a greatly simplified sperm ary : the single proximal cell 



mi. 



FIG. 85. Reproduction and Development of Salvinia. 



A, portion of a submerged leaf, showing three sori in vertical section, 

 two containing microsporangia (mi. spg} and one megasporangia (mg. 

 spg}. (x 10.) 



B, a germinating microspore (mi. ste\ showing the vestigial prothallus 

 (prth} and spermary (spy}. ( x 150.) 



c, diagrammatic vertical section of a germinating megaspore, showing 

 the outer (mg. sp} and inner (nig. sp'} coats of the spore, and its cavity 

 (c) containing plastic products, separated by a septum (d] from the pro- 

 thallus (prth}, in which two ovaries (ovy} are shown, that to the left 

 containing an ovum, that to the right a polyplast. ( x 50.) 



D, megaspore (mg. sp} with prothallus (prth} and phyllula just begin- 

 ning to develop into the leafy plant : st, stem ; cf, cotyledon ; and /, 

 outermost leaf of the terminal bud. ( x 20.) 



(A and B, after Sachs ; D, after Pringsheim.) 



(prth) of the filament arising from the microspore, a still 

 more simplified prothallus. Both prothallus and spermary 

 are vestigial structures ; the prothallus is microscopic and 

 unicellular instead of being a solid aggregate of considerable 

 size, as in the two preceding types ; the spermary is bicellular 



B B 



