356 



BOTANY. 



exospore, which is generally yellow in color. Internally 

 the spores contain, in addition to the protoplasm, oil-drops 

 and chlorophyll granules. 



465. — In the germination of the spores, the exospore is 

 ruptured, and the endospore protrudes as a tubular filament, 

 which elongates by the continued growth of an apical cell ; 

 partitions form at close intervals, and the threads branch 

 freely, giving rise to a green Conferva-like mass, the pro- 

 tonema (Fig. 245, £). In the Sphagnacece, however, the 

 protonema is a fl^attened mass, somewhat like the plant-body 



Pis;. 345. — Development of PimaHa hygrmnetHca, A, germinating pporee ; «, rup- 

 tnrea exospore ; w, w, young root hairs — on the opposite side of the spore is the 

 beginning of the protonema ; i\ vacuole in a germinating spore. B, part of a proto- 

 nema three weeks after germination ; A, a primary shoot with brown walls— from it 

 arise several lateral branches b. K^ a young bud or rudiment of a leaf-bearing 

 axis ; jo, a small root hair. J. X 550 ; .B X 70.— After Sachs. 



of the lower Liverworts. After a greater or less period of 

 vegetation, there arise upon the protonema small buds, which 

 develop into leaf -bearing axes (Fig. 345, B, K). These buds 

 originate from single cells, which repeatedly divide them- 

 selves by diagonal partitions ; the apical cell thus formed 

 in each case becomes the apical cell of the bud, and the 

 new axis. The leafy axes thus formed sooner or later bear 

 the sexual organs, thus completing the round of life. 



466. — Mosses reproduce themselves asexually, sometimes 

 in a manner quite similar to that of the Liverworts — e.g., in 



