192 



ELEMENTS OF STRUCTURAL BOTANY. 



342. We shall now consider the mode of reproduction 

 in the Mosses. Let us commence with the spore. This, 

 upon meeting with proper conditions, bursts its outer 

 coat (the exospore), and the inner 

 coat (the endospore) is then pro- 

 truded as a slender tube. This 

 continues to grow by repeated divi- 

 sion, until at length, in most cases, 

 a tangled thread-like mass of vege- 

 tation is produced, to which the 

 name protonema has been given. 

 After the lapse of several days 

 Fig. 240. minute buds are developed at differ- 



ent points upon the protonema, and these are found to 

 consist of whorls of scaly leaves. This is the beginning 

 of the development of the ordinary Moss-plant. Upon 

 the plants thus arising from the buds are developed 

 antheridia and archegonia, 

 the former in the axils of 

 the leaves forming the 

 rosettes shown in Fig. 240, 

 and the latter at the apex 

 of other stems, as shown in 

 Fig. 239. The antheridia 

 are seen under the microscope 

 bo be club-shaped bodies, containing a mass of cells in 

 which the antherozoids are formed. The archegonia are 

 flask-shaped bodies, with a lower expanded portion and a 

 long neck above. Fig. 242 shows the apex of a fertile 



Fig. 240. Apex of sterile stem, showing rosette of perigonial leaves, in the 

 axils of which are the antheridia ; greatly enlarged. 



Fig. 241. Enlarged view of capsule, showing peristome and detached oper- 

 3Uluin. (Wood and Steele.) 



Fig. 241. 



