SEXUAL REPRODUCTION. 



295 



and the decay of the ovary. Such are the resting spores of 

 Spirogyra, Mucor, Cystopus, and Char a* 



400. Embryo. — In the other case the sexually produced 

 spore develops at once. Except in the brown seaweeds, 

 whose eggs are ejected into the water before fertilization, the 

 spore remains enclosed in the ovary, within which it begins 

 to form an embryo. 



401. Induced growth. — As a consequence of this develop- 

 ment, growth is induced in the ovary itself and the parts 

 adjacent. In the mildews the ovary produces one or more 

 asci (fig. 224), while the hyphae near by branch profusely and 

 cover the developing internal parts with a thick false tissue 

 (figs. 223, 337), the whole constituting a fructification. In 



Fig. 337. — Formation of the " fruit" in a mildew {Rrysipke Cichoriacearuni). a, 

 threads of mycelium ; b, spermary ; c, ovary ; d, the ovary after fertilization, show- 

 ing the branches from hypha beneath ovary covering it ; e, later stage, showing 

 these branches coalescent and dividing by partitions to form a false tissue. (Com- 

 pare fig. 223.) Highly magnified. — After (Ersted. 



red seaweeds the ovary and adjacent parts finally form the 

 cystocarp (fig. 330). In mosses the ovary grows extensively 

 (fig. 338), but is finally torn loose and carried up on the 

 embryo and becomes the loose hood, which is usually lost 

 early. The stem also enlarges beneath the ovary and forms 

 a sheath around the embryo (fig. 338), which grows down- 

 ward into the parent though not organically connected with 



* It should be remembered that thick-walled 

 formed vegetatively. See ^[ 308. 



resting spores" are 



also 



