130 Minnesota Plant Life. 



vided that all the spores found the opportunity of germination. 

 Such little clumps of spores, originating by the partition of a 

 fecundated egg, then underwent a division of labor, so tliat the 

 superficial spore-mother-cells acquired the character of capsule- 

 wall-cells and did not ordinarily retain the power of spore- 

 production. This was in order to protect the cells of the in- 

 terior, which remained as true spore-forming cells, and there is, 

 in such an instance, a fundamental peripheral sterilization of the 

 spore-mass, so that it comes to consist centrally of functional 

 spore-mother-cells while sterilised spore-mother-cells take the 

 character of wall tissue. Really, by this time, a new kind of 

 organism has come into existence, something entirely unlike 

 anything in ordinary animal life-histories. 



The new organism, beginning thus simply as a mass of 

 spores, then in higher types assuming the form of a mass of 

 spores enclosed in a wall, underwent further improvement in 

 other families of liverworts and mosses until finally it became 

 a large capsule with long slender stalk, several layers of wall 

 cells and a supporting column of sterile cells running up the 

 middle. By means of such improvements the possible number 

 of spores was increased and they were better managed by the 

 plant ; for when the spores of a moss are distributed from a cap- 

 sule on a tall slender stalk they will fall farther on every side, 

 thus obtaining more favorable chances of persistence than if 

 scattered from a short-stalked capsule. 



To the philosophical botanist this profound need of coun- 

 terbalancing the unfavorable conditions of the environment 

 suggests itself as the occasion of erect habit in herbs, shrubs 

 and trees. By maintaining the erect position i)lants can also 

 enjoy better illumination ; but it may be safely assumed, for the 

 reasons that have been given, that the erect position and the 

 slender habit of growth of the moss-fruit, based as it is upon 

 an instinctive effort to enlarge the opportunities of spores, is the 

 precursor of all erect habits in the terrestrial spore-producing 

 areas of plants, — and essentially all plant shoots are spore-pro- 

 ducing areas. Pine trees, for example, develop i)ollen, a form 

 of spores, in their little cones. Roots never develop spores, and 

 may be regarded as derivatives of that original end of the cap- 



