THE PAST HISTORY OF PLANTS. 209 



the mushroom, the puff-ball, and all those oth- 

 er large and curiously-shaped forms commonly 

 lumped together in popular language under the 

 name of toadstools. Their anatomy and physiol- 

 ogy is extremely complex. 



To recapitulate; CELLULAR PLANTS belong to 

 two main types ; those which contain chlorophyll, 

 and live like plants by eating and assimilating 

 carbon under the influence of sunshine ; these are 

 generally grouped together in a rough class as 

 ALG^E : and those which contain no chlorophyll, but 

 live, like animals, by using up or destroying the 

 carbon-compounds already stored up by green 

 plants ; these are generally grouped together in 

 a rough class as FUNGI. 



The lichens form a curious mixed group, whose 

 strange habits cannot here be described at any 

 adequate length ; they are not so much separate 

 plants as united colonies of algae and fungi, in 

 which the green alga does the main work of col- 

 lecting food, while the parasitic fungus, increasing 

 with it at the same rate, eats it up in part, while 

 contributing in turn in various ways to the gen- 

 eral good of the compound community. This is 

 therefore hardly a case of pure destructive para- 

 sitism, but rather one of a co-operative society 

 banded together on purpose for mutual advan- 

 tage. 



The mosses and liverworts, once more, show 

 us an intermediate stage between the true cel- 

 lular and the true vascular plants. They have 

 a rudimentary stem, and beginnings of vessels. 

 They have also leaves, or organs equivalent to 

 them ; and they display the first approach to 

 something like flowers. 



14 



