Minnesota Plant Life, 155 



instead of remaining perched upon the sexual plant at the point 

 where its parental egg-organ was developed, it had the knack 

 of stepping off and driving its own root-system into the soil it 

 would be entirely independent. This, however, is exactly what 

 the ancestral fern capsular plants are supposed to have done, so 

 that the fern plant as it grows in the woods may be compared 

 properly, not to the leafy moss-plant but to a very highly im- 

 proved moss capsular plant with leaves and roots of its own. 



A primitive attempt to develop a special leaf-area is seen in 

 the capsules of the dung-mosses. In these the region between 

 the capsule proper and the stalk is flared out into a green collar 

 and this is essentially a starch-making expansion of the general 

 plant surface. But that is precisely what a leaf is structurally, 

 for it also may be described as normally a starch-making expan- 

 sion. It is true a great many leaves come in higher forms to as- 

 sume entirely different functions, but the appearance of the leaf 

 must be regarded as connected with starch-making, for orig- 

 inally this was probably the function of all leaves, however far 

 some modern forms may have abandoned it. 



Had the moss capsular plants not originally given up, in the 

 peat-moss types, the power of growing continuously, or if they 

 had independently attained this power, there is no reason why 

 they should not have given rise to many interesting and complex 

 higher forms. But no matter how perfect a moss capsular 

 plant may become, no matter how skillfully it may distribute its 

 spores, or provide for the manufacture of starch by its own leaf- 

 green independent of the parent sexual plant, it always comes 

 to a point when it is completely mature, can develop no farther, 

 must eject its spores and perish. For this reason mosses con- 

 stitute what is called a terminal type and there are no higher 

 forms of plants regarded as derived from them. 



