Schneider : the phenomena of symbiosis. 927 



nected with some form of symbiotic relationship of organisms. 

 One needs but call to mind the recent discoveries in the treat- 

 ment of disease, modern surgery, agriculture, dairy industries, 

 etc. A mere mention of all the experimentation and discoveries 

 in connection with symbiosis would fill volumes. The object of 

 this paper is simply to define the various phenomena of sym- 

 biosis according to the present status of our knowledge and to 

 indicate some of the difficulties encountered in the treatment of 

 the subject. Much careful research is yet necessary in order 

 to clear up the uncertainties in regard to the biological signifi- 

 cance of many of, the symbioses. In order to impress this un- 

 certainty more fully we shall mention a few symbiotic phen- 

 omena which are either not recognized as such or improperly 

 classified, usually as parasitism. 



UNCLASSIFIED SYMBIOTIC PHENOMENA. 



Under this heading will be briefly mentioned numerous and 

 varied phenomena which are of. undoubted symbiotic nature, 

 but are not understood or have not been sufficiently studied to 

 give them a definite position in the system of symbioses here 

 proposed. Some of these phenomena are of a very compli- 

 cated nature and indicate a long phylogenetic development. 

 In many instances the morphological adaptation and relation- 

 ship of the organisms is so remote as to awaken serious doubt 

 as to its symbiotic nature. Under this category belong the 

 mutual adaptation of plants (entomophilous and other flowers) 

 and animals; also the various forms of mimicry, the association 

 of various species of aphidae and ants upon certain plants, be- 

 sides many other phenomena. The association of trees, such 

 as the myrmocophilous Cecropias and representatives of other 

 genera, with ants, is by many designated as true mutual istic 

 symbiosis. In reality, however, the mutual morphological and 

 functional adaptations are as remote as in some of the instances 

 just cited. 



The relation of the male and female reproductive cells is of 

 a truly symbiotic nature. It represents a most specialized 

 individualism. The relationship existing between the imma- 

 ture embryo and the food- supplying parent-stock is evidently 

 a form of symbiosis. There are numerous instances in both the 

 animal and vegatable kingdom in which the more or less imper- 

 fect but complete second generation lives in a symbiotic rela- 

 tionship with the first generation. The relationship existing 

 between sporophytic and gametophytic generations can not be 



