240 BULLETIN 94. 



A branch antheriditim is developed as a lateral branch of the 

 oogoniophore, arising usually quite near the oogonium, but some- 

 times more or less remote from it, rarely on a separate hypha. 

 The branch grows towards the oogonium and its rounded end 

 comes in contact with the oogonium wall and becomes fixed at the 

 point of contact. A septum is now formed in the branch cutting 

 off an elongated cell varying from 15/4-40;'.. This cell, one 

 end of which is in contact with the oogonium wall, is the anthe- 

 ridium, and the proximal portion of the branch is the antheridio- 

 phore. More than one antheridium may be formed in connection 

 with a single oogonium, frequently two and sometimes three. 

 Both may be branch antheridia, or one may be a branch antherid- 

 ium and the other a stalk antheridium, and other combinations 

 may take place where more than two antheridia are present. 

 There does not seem to be any rule in the number of antheridia 

 which take part in the fertilization of the egg cell. Where several 

 are in contact one or more may take part in the act of fertilization. 



When the antheridial cell is formed its farther development is 

 the same whether it be a branch antheridium or a stalk antherid- 

 ium. The cell which is cylindrical or nearly so in form begins to 

 swell and this continues until it is two to three times the original 

 diameter, the greatest diameter being near the end which is in 

 contact with the wall of the oogonium. At the same time it also 

 becomes quite strongly curved and more or less twisted. In case 

 the oogonium is a terminal one and possesses both a stalk anther- 

 idium, and branch antheridium, the stalk antheridium may curve 

 so strongly to one side as to make it difficult to determine later 

 which is really the stalk antheridium. 



While these changes are taking place in the antheridium the 

 granular protoplasm of the oogonium is moving toward the center 

 to form the egg cell as described above, and now the end of the 

 antheridium in contact with the wall of the oogonium, puts out a 

 slender tube which pierces the oogonium wall, extends across the 

 space occupied by the peri plasm and touches the egg cell at the 

 nearest point. This tube is known as the fertilization tube. At 

 this point on the egg cell there is a small clear space called the 

 receptive spot. 



Nearly all of the protoplasm in the antheridium except a very 



