34 SEX AND HEREDITY 



the. time of fertilization. This immediately raises the 

 question of how syngamy is effected in the Ferns and 

 other primitive Land-Living Plants. 



The method of syngamy in Ferns may be held to 

 represent fairly that of all the more primitive Plants of 

 the Land. Its main features have been described in the 

 previous Lecture. The spermatozoid, set free and motile 

 in water (Fig. 12 (6, 8)), and the ovum, deeply seated in 

 the archegonium (Fig. 13), are the gametes. The problem 

 is to bring them together with certainty. The medium 

 of transit is water. It is only in presence of water that 

 the antheridia and archegonia open. In Nature this is 

 provided by showers, or copious dews, and into that 

 water the spermatozoids escape. A significant fact is 

 that the spermatozoids are very numerous. But still 

 the prospect of the fusion of spermatozoid and ovum 

 being carried out would be almost infinitely small were 

 it left to mere chance. The ovum, lying protected in 

 the cavity of the archegonium, would almost inevitably 

 be missed in random wanderings of even numerous 

 spermatozoids. But any microscopic preparation of 

 them in the living state shows that the spermatozoids 

 are attracted, and enter the archegonium with certainty, 

 and in large numbers. Experiment has explained the 

 source of the attraction. 



If artificial archegonia be made in the form of minute 

 glass flasks, it would be possible to fill them with solutions 

 of various soluble substances. If they were then immersed 

 in water the soluble substance would diffuse out, the neck 

 of the flask being constantly the centre of greatest con- 

 centration. If the water contained living spermatozoids, 

 the effect of each substance used could be noted, according 

 as it influenced their movements. In this way a number 



