CLASSIFICATION OF SYMBIOTIC PHENOMENA 251 



plants and obtain from them food of a carbonaceous character 

 but without apparently injuring the green symbiont." Lichens 

 and mycorhizas are cited as examples. 



Atkinson (1) states that "symbiosis means a living with or 

 living together, and is said of those organisms which live so 

 closely in connection with each other as to be influenced for 

 better or worse, especially from a nutrition stand-point." This 

 obviously includes all parasitism under symbiosis. 



Cowles (3) defines symbiosis thus: "When two or more di- 

 verse organisms live together in more or less intimate relation- 

 ship the phenomenon is termed symbiosis. The phenomena in- 

 cluded under symbiosis may be conveniently grouped under the 

 subheads parasitism and commensalism." 



Warming (11) does not give a concise definition but in a foot- 

 note he says: "A somewhat extended significance is here given 

 to the term symbiosis." He then includes in his discussion of 

 symbiosis practically all of the interrelations of plants with each 

 other and with animals. 



The above quotations are enough to show that there is consid- 

 erable variation in definition and in the kinds of phenomena 

 included under symbiosis in the writings of present-day workers. 

 Let us now turn our attention to the earlier writers. 



Obviously the surest Avay of getting at the meaning of the 

 word as understood by the earlier writers is to obtain the opinion of 

 the one who first introduced the term to botanical literature, 

 namely DeBary. De ^ary (5) defined symbiosis broadly as 

 the living together of dissimilar organisms. " . . . . der 

 Ercheinungen des Zusammenlebens ungleichnamiger organismen, 

 der Symbiose, wie man kurtz and algemein sagen kann." That 

 he regarded it a broader term than parasitism is shown by the 

 fact that he says: "Die bekannteste and exquisiteste Erschei- 

 nung der Symbiose ist der Volstandige Parasitismus . 

 The further discussion by De Bary proves beyond a doubt that 

 he intended to include under symbiosis all phenomena of the 

 intimate association of dissimilar organisms. He mentions, for 

 instance, epiphytes, Azolla and bluegreen algae, pollinating in- 

 sects and flowers, etc. If, then, this represents accurately De 



