LYCOPODIALES 325 



homologous one with another,- and the spores that they produce 

 homologous also. It is only a step further to a condition where 

 the sporangia and spores are all alike, in structure and in size, up 

 to full maturity. This state is actually seen in Lycopodium, in 

 most Ferns, and in all Mosses, which are accordingly styled homo- 

 sporous. The condition with the spores differing in size is called 

 heterosporous. From the evolutionary point of view the latter is 

 the later and derivative state, and it has been adopted exclusively 

 by all the higher Land-growing Plants. The homosporous is the 

 more primitive state, and it will now be illustrated in the Ferns and 

 Mosses ; plants which in this, as well as in other respects, stand lower 

 in the scale of Evolution. 



