THE ORIGIN OF SEX IN PLANTS 31 



Algae. The behaviour, and often approximately the 

 proportions of the pairing gametes of the lower vegeta- 

 tion of the Land, such as the Mosses and Ferns, remain 

 substantially the same as in the Algae. From Fern-like 

 plants a gradual transition has led to the state seen in 

 the Flowering Plants. But though in them the male 

 gamete is no longer motile, the fusion of the gametes 

 is still a coalescence in which the nuclear fusion is an 

 essential feature. When stripped of all accessories, many 

 of which find their explanation in the varied circum- 

 stances under which plants live and propagate, the 

 actual fact of sexuality has remained the same for them 

 all. We conclude then that syngamy consists for Plants 

 at large in the coalescence of two sexual cells of more or 

 less distinct origin, and especially of the nuclei which those 

 cells contain. There may be, and there are, differences in 

 the mechanism by which this syngamy is brought about 

 in Plants of various habitat and character. The next 

 Lecture will be devoted to a study of those differences 

 of method, and to the varied circumstances to which 

 those differences may be ascribed. 



