46 



BOTANY. 



side where the brown speck, seen while still within the antheridium, is con- 

 spicuous. 



The act of fertilization may be easily observed by laying fresh anthe- 

 ridia into a drop of water containing recently discharged egg cells. To 



obtain these, all that 

 is necessary is to al- 

 low freshly gathered 

 plants to remain in 

 the air until they are 

 somewhat dry, when 

 the ripe sexual cells 

 will be discharged 

 from the openings of 

 the conceptacles, ex- 

 uding as little drops, 

 those with antheridia 

 being orange-yellow; 

 the masses of oogonia, 

 olive. Within a few 

 minutes after putting 

 the oogonia into water, 

 the egg cells may be 

 seen to escape into the 

 water, when some of 



the antheridia may be 

 FIG 27. - H, the eight egg cells still surrounded by ^ ded The sperma . 

 the inner membrane of the oogomum. 7, the egg 



cells escaping into the water. J, a single egg cell tozoids will be quickly 

 surrounded by spermatozoids. K, mass of sperma- discharged, and collect 

 tozoids surrounded by the inner membrane of the . ,. , , 



antheridium. L, spermatozoids. M, young plant. immediately in great 

 r, the roots. K, x 300 ; L, x 600 ; the others, x 150. numbers about the egg 



cells, to which they 



apply themselves closely, often setting them in rotation by the movements 

 of their cilia, and presenting a most extraordinary spectacle (J). Owing to 

 the small size of the spermatozoids, and the opacity of the eggs, it is im- 

 possible to see whether more than one spermatozoid penetrates it ; but 

 from what is known in other cases it is not likely. The egg now secretes 

 a wall about itself, and within a short time begins to grow. It becomes 

 pear-shaped, the narrow portion becoming attached to the parent plant or 

 to some other object by means of rootlets, and the upper part grows into 

 the body of the young plant (Fig. 27, M). * 



