THE ALG7E. 77 



breaks away, leaving the naked protoplasm within ex- 

 posed. This protoplasm is the female gamete ; it is some- 

 what ovoidal in shape, is coarsely granular, and is of a 

 dark green color. 



The antheridium is longer and more slender and is 

 curved. It is lighter in color, as there is but little chlo- 

 rophyl present. The distal end becomes cut off from the 

 rest by a transverse partition ; the protoplasm of this por- 

 tion breaks up into numerous antherozoids, each having 

 a pair of flagella, the male gametes. 



When fully mature, the antherozoids swim out through 

 the upturned outer end of the antheridium and find their 

 way to the entrance of the oogonium. One, at least, of 

 the antherozoids fertilizes the ovum. A resting spore is 

 thus formed, which assumes a reddish-brown color, be- 

 comes encysted in a thick cellulose wall, and develops 

 oil globules in the interior. After its period of rest, the 

 resting spore develops into an ordinary Vaucheria plant, 

 which passes through several generations by the asex- 

 ual mode of reproduction before resting spores are again 

 formed. Draw a typical pair of the reproductive organs. 



References for Reading. Parker's "Practical Biology," pp. 169- 

 175 ; Dodge's " Elementary Practical Biology," pp. 267-272 ; Boyer's 

 " Elementary Biology," pp. 124-127; Bower's "Practical Botany," pp. 

 429-436 ; Goebel's " Classification of Plants," pp. 32-34 ; Strasburger 

 and Hillhouse's "Practical Botany," pp. 250-254 ; Sachs' " Physiology 

 of Plants," pp. 732-734 ; Bennett and Murray's " Cryptogamic Botany," 

 pp. 280-282; Carpenter's "The Microscope," pp. 491-493. 



The Volvocineae. The characteristic that distinguishes 

 these plants is the formation of a coenobium, which is a 

 colony composed of cells that result from repeated fissions 

 of a mother cell. The number of cells that compose the 

 colony is always some multiple of two. These cells are 

 held together in regular form by a sheath of a gelatinous 

 nature. Here are included some forms of singular beauty 



