84 



PLANT-LIFE 



hairs (paraphyses) whose tips are directed towards the 

 opening of the conceptacle. The male organ produces 

 sixty-four almost colourless, oval, biciliated spermato- 

 zoids. The egg-cell divides into two. The ova and 

 spermatozoids are eventually expelled from the con- 

 ceptacle, and fertilization ensues outside the parent 

 plant. Only one spermatozoid is permitted to coalesce 

 with an ovum in the fertilizing act. It is apparent that 



the male elements are 

 produced in excess of the 

 actual requirements in 

 order that there may be 

 no risk of failure in the 

 nuptials ; one sperma- 

 tozoid might miss the 

 mark, and were but one 

 produced the risk would 

 be great. The fertilized 

 egg-cells become sur- 

 rounded with cell-walls 

 and germinate without 

 entering upon a rest- 

 ing stage, the product of 

 germination being, of course, a new Pelvetia plant. 

 From this short account it will be seen that sex is well 

 developed in Pelvetia. We have the well-nourished, 

 passive egg-cell and the tiny life-bearing body of an 

 hour, the spermatozoid. The sexes are clearly distin- 

 guished, and that they are firmly established is evident 

 from a fact we have not noted — an egg-cell will not 

 give rise to a new plant unless it has been fertilized. 

 This, the reader will have observed, is not always 



Fig. 29.— Pelvetia. x 260. 



a, a, Antheridia (male organs); p, p, 



paraphyses or barren hairs. 



