VIII] THE MAIDEN HAIR TREE 125 



the vegetable kingdom. It was, therefore, with no 

 ordinary interest that Hirase's discovery was received, 

 as it broke down a distinction between the two great 

 divisions of the plant- world which had been generally 

 accepted as fundamental ; though it is only fair to 

 say that the German botanist Hofmeister, a man of 

 exceptional originality and power of grasping the 

 essential, foresaw the possibility that this arbitrary 

 barrier would eventually be removed. The Ferns 

 and other plants in which the male cells are motile, 

 represent earlier stages in the progress of plant 

 development, when the presence of water was essen- 

 tial for the act of fertilisation, a relic of earlier days 

 when the whole plant-body was fitted for a life in 

 water. As higher types were produced, the plant- 

 machinery became less dependent on an aqueous 

 habitat, and the loss of organs of locomotion in the 

 male cells is an instance of the kind of change 

 accompanying the gradual adaptation to life on 

 land. The idea of the gradual emancipation of plants 

 from a watery environment is expressed in a some- 

 what extreme form by the author of a book entitled 

 The Lessons of Evolution (52), who states that the 

 ocean is the mother of plant-life and that plants 

 formed the army which conquered the land. In 

 Ginkgo we have a type which, though similar in 

 most respects to the (.Conifers, possesses in its motile 

 reproductive cells a persistent inheritance from the 



