110 PRACTICAL BOTANY. 



in both Chara and Nitella and state how many cells com- 

 pose it in each. When the egg cells are ready for fer- 

 tilization, antherozoids, which have been set free in the 

 water by the ripening of the antheridium, swim to the 

 crown, find passage down through a central opening be- 

 tween its cells, enter, and fertilize the egg. The egg now 

 matures, protected by its covering of cells. In time the 

 archegonium drops off from the mother plant, sinks to the 

 bottom in situ, or is carried by currents to other localities. 

 When the conditions are again favorable, it germinates 

 and produces a new plant. Draw an archegonium. 



References for Reading. Bidgood's "Elementary Biology," pp. 

 85-111; Parker's "Elementary Biology," pp. 206-220; Bennett and 

 Murray's " Cryptogamic Botany," pp. 173-183 ; Goebel's " Classifica- 

 tion of Plants," pp. 52-64 ; Carpenter's " The Microscope," pp. 505- 

 509 ; Sachs' " Physiology of Plants," pp. 95, 96, 453, 454 ; Strasburger 

 and Hillhouse's "Practical Botany," pp. 37, 202 f, 254 g; Vines' 

 " Text-Book of Botany," pp. 251-255 : Huxley and Martin's " Practi- 

 cal Biology," pp. 430-442 ; Dodge's "Practical Biology," pp. 273-284; 

 Boyer's " Elementary Biology," pp. 128-133 ; Campbell's " Structural 

 and Systematic Botany," pp. 37-40 ; Bessey's " Essentials of Botany," 

 pp. 180-182; Bower's "Practical Botany," pp. 409-418. 



CLASS II. The Brown Algae (Phaiophyceoe). A decided 

 advance in the tissues of the plant thallus arid the position 

 of the cilia on the sides of the base of the pointed end of 

 the zoospores, are characteristics which distinguish the 

 Brown Algae from the Green Algae. Chlorophyl is pres- 

 ent, but is rendered invisible by the presence of a brown 

 coloring matter, pJiycophcein, which is probably a dif- 

 ferentiation product from the chlorophyl. The fertili- 

 zation is isogamous in the lowest plants ; in the higher 

 forms it is oogamous. In many of the plants of this 

 group, however, the process of the sexual fertilization is 

 still unknown. There are two subdivisions based on the 

 character of the swarm spores, the Phceosporece and the 



