BEYOPHYTES 303 



duces only sexual spores (oospores), and therefore produces 

 sex organs and gametes. It is known, therefore, as the 

 gametophyte — that is, " the gamete plant." 



The generation which consists of the " spore fruit " — ■ 

 that is, leafless stalk and spore case — produces only asexual 

 spores, and is called the sporophyte — that is, "the spore 

 plant." 



The relation between the two alternating generations 

 may be indicated clearly by the following formula, in 

 which G and S are used for gametophyte and sporophyte 

 respectively : 



G=S>o— S— o— G=8>o— S— o— G, etc. 



The formula indicates that the gametophyte produces 

 two gametes (sperm and egg), which fuse to form an oospore, 

 which produces the sporophyte, which produces an asexual 

 spore, which produces a gametophyte, etc. 



In reference to the sporophytes and gametophytes of 

 Bryophytes two peculiarities may be mentioned at this 

 point: (1) the sporophyte is dependent upon the gameto- 

 phyte for its nourishment, and remains attached to it ; (2) 

 the gametophyte is the special chlorophyll-generation, and 

 hence is the more conspicuous. 



If the ordinary terms in reference to Mosses be fitted 

 to the facts given above, it is evident that the " moss 

 plant " is the leafy branch of the gametophyte ; that the 

 " moss fruit " is the sporophyte ; and that the alga-like 

 part of the gametophyte has escaped attention and a 

 common name. 



The names now given to the different structures which 

 appear in this life history are as follows : The alga-like part 

 of the gametophyte is the protonema, the leafy branch is 

 the gametophore (" gamete-bearer ") ; the whole sporophyte 

 is the sporogonium (a name given to this peculiar leafless 

 sporophyte of Bryophytes), the stalk-like portion is the seta, 

 the part imbedded in the gametopnore is the foot, and the 

 urn-like spore-case is the capsule. 



