20 FLOWERLESS PLANTS 



gymnosperm and an advanced crj-ptogam, such 

 as Selaginella, shows a remarkable resemblance 

 between the processes of reproduction. In the 

 latter plant two kinds of spores are produced. 

 One sort, of which a large quantity is developed, 

 are known as the microspores, the others, of 

 which there are comparatively few, have been 

 called the megaspores. Now it is an estabhshed 

 fact that the microspores in their production 

 and form closely resemble the poUen grains of 

 the cone-bearing plant. As weU, there is a 

 remarkable resemblance between the mega- 

 spores and their development, and the female 

 organs in the cone tribe. 



In the case of the Selaginella the settle- 

 ment of the spores in a suitable situation is 

 followed by the formation of an independent 

 organism — the prothallns. The microspore 

 forms one kind of prothallus (in this case 

 rather insignificant) on which the antheri- 

 dium, or the male organ, is borne. The 

 megaspores are responsible for another sort 

 of prothallus, on which the female cells are 

 to be discovered. The act of fertihsation is 

 carried on under water, which may be present 

 in the form of dew or rain drops. It consists in 



