260 THE LIFE OF THE PLANT 



endowed with a double movement : they move quickly 

 forward and also rotate round their axis. Thu,s fer- 

 tiHsation, secured in seed plants by complicated adap- 

 tations by which the non-motile pollen of a flower is 

 transferred to a stigma, is here accomplished by the 

 motility of the male cells themselves, the antherozoids.^ 

 The antherozoids of mosses are most easily seen. If in 

 the spring we gather a stem of a big moss, which forms 

 round, soft, green tufts in woods and marshes, and if we 

 press between the fingers the unsightly brown clusters of 

 modified leaves, seen at that season at the ends of many 

 of the stems, small whitish drops will exude. Everj.' such 

 drop will contain millions of antherozoids. Fig. 75, II. 

 shows the fertilisation of a female cell of a seaweed, 

 found in the Baltic Sea and called Fucus. This cell is 

 non-motile by itself, but antherozoids swarm round it, 

 often surround it with a thick layer, and thus carry it 

 away with them. 



Thus, the vegetable world observed under the micro- 

 scope turns out to be full of motion : in the cells of the 

 water-melon the protoplasm moves ; in every weedy pool 

 there swarm myriads of zoospores ; in the drops of 

 evening dew there move the antherozoids of mosses 

 and ferns, finding their way to female cells in order to 

 fertilise them. But do we not notice phenomena of 

 motion in a more obvious form, in those organs and 

 plants that we can observe with the naked eye and 

 which are naturally associated in our minds with the 

 word ' plant ' ? Such phenomena can indeed be easily 

 demonstrated, although they do not occur as often 

 as microscopic movements. They are especially striking 

 in plants growing in warm countries or in our hothouses ; 

 the reason of which is easily understood. All kinds of 

 motion in plants are accelerated with rise of tempera- 



1 We have noticed in the previous chapter that antherozoids have been 

 discovered in the pollen-tubes of some plants. In the next chapter we 

 shall be able to appreciate the importance of this fact. 



