146 



BOTANY. 



suit of their coming together is the fertilization of the germ- 

 cells, and their transformation into resting spores by the 

 secretion of a wall of cellulose on each one. 



300. In germination the resting spore lengthens and un- 



Fis. 73.— Sexual organs of Eookweed (F. vesiculosis). A, antherids; B, an- 

 therozoids; /, oSgone and hairs; II, escape of germ-cells; III, germ-cell sur- 

 rounded by antherozoids; IV, K, germination of resting spore. Magnified 160 

 times; £,360. 



dergoes division into numerous cells; at the same time it 

 elongates below into root-like processes, which serve to 

 hold fast the new plant ( V, IV). 



Practical Studies. — («) Secure specimens of Rockweeds, fresb or 

 dry. Fresh ones may easily be found along the beach of the ocean 

 after a storm. Dry specimens can easily be procured by purchase or 

 exchange. Make thin cross-sections through the conceptacles in the 

 thickened ends of the branchlets. When mounted in water, even 

 the sections from tlie dry specimens will frequently show the sexual 

 organs quite well. It must be remembered that some species are 

 dicEcious, i.e., have the antherids on one plant and the oi)gones on 

 another. 



