6 INTRODUCTORY - 



senses of its own, none the less remarkable than those of the 

 animal and far better adapted to its own peculiar development. 

 It has, for instance, evolved a marvelous relation to gravity and a 

 peculiar sensitiveness to light unknown among animal life, besides 

 other special senses. 



Both animals and green plants have developed and maintained 

 sex reproduction. Moreover the animal has developed sex indi- 

 viduality to a very marked degree. Among the plants, a high de- 

 gree of complexity became possible, only when the principle of 

 alternation of generations reduced the sexual growth to a minimum, 

 and correspondingly magnified the possibilities of asexual develop- 

 ment. Although the animal lost its physical independence when 

 it ceased to produce its own food from inorganic matter, by per- 

 sistently maintaining the idea of sex and sexual individuality, 

 and perfecting its method of locomotion, and with this the acute- 

 ness of its special senses, it has made possible the later evolution 

 of the highest possible development of life, refined and perfected 

 in ourselves. 



We have thus emphasized the distinctions between green plants 

 and animals because there has been a third line of evolution lead- 

 ing from the simpler green plants w^hich commenced its divergence 

 in nearly the same points as the animals, but which has had a far 

 different history and has attained a widely different development. 



Whether we are aware of their existence or not, there are in 

 the world about us a vast array of more or less inconspicuous 

 organisms that are known to botanists under the name of fungi. 

 These differ among themselves in size and structure far more 

 widely than do a violet and an oak, and many of them at 

 first sight would seem to bear so little resemblance to one 

 another as to possess no real relationship. Many of them are 

 known more or less popularly under common names such as 

 moulds, mildews, mushrooms, toadstools, puff-balls, rusts, smuts, 

 leaf-spots, blights — each popular name indicating a more or less 

 indefinite group of plants, more or less closely related to one an- 

 other. They grow in every conceivable place wherever organic 

 matter can be found which will serve as their food, and a moderate 

 degree of heat and moisture are present to furnish the necessary 

 conditions of growth. Decaying fruits or vegetables, oily bones, 

 old musty shoes, wet paper, the dead stems of herbaceous or semi- 



