XXXII 



REDUCTION OF THE GAMOBIUM 



441 



The contents of the megaspore are divisible into a com- 

 paratively small mass of protoplasm at one end, and of starch 

 grains, oil-globules, and proteid bodies, which fill up the rest 



mi.sp 



FIG. 115 Reproduction and Development of Saivtnia. 



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

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

 spg). (x io.) 



B, a germinating microspore (mi. spg), showing the vestigial prothallus 

 (prth) and its two spermaries (spy). ( x 150.) 



c, diagrammatic vertical section of a germinating megaspore, showing 

 the outer (mg. sp) and inner (mg. sp 1 ) 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 ; ct i cotyledon ; and /, 

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



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



(c, c) of the spore. The megaspore has, in fact, attained its 

 large size by the accumulation of great quantities of plastic 

 products, which serve as nutriment to the future prothallus 



