THE AMERICAN 



MONTHLY 



MICROSCOPICAL JOURNAL. 



Vol. XVII. MARCH, 1896. No. 3. 



Symbiosis: or, Partnerships in Plant-Life. 



BY PROFESSOR WEISS. 



WITH FRONTISPIECE. 



From Proceedings Manchester Microscopical Society. 

 So mucli has been said and written about the keen com- 

 petition of plants and animals in the great struggle for 

 existence that we are apt to picture the organic world as 

 a huge battlefield in which each individual is waging 

 war against the rest of the organic world. There is no 

 doubt some truth in such a view as this, still it repre- 

 sents anything but the wliole truth. The struggle for 

 existence, we are told, grows more and more pronounced 

 the closer allied the organisms are. In animals of the 

 same species therefore, competition should be most pro- 

 nounced; yet that is not always the case, for we find that 

 many species are of gregarious habit, a habit which 

 would be detrimental where struggle for existence is 



LIST OF ILLUSTRATIONS. 



(1) Pdrtiou of stem of Cecropia showing (4) Koot of a tree affected by a micorhiza, 



hollow stem which is imhabited by and thus curiously altered in shape, 



ants, aud aperture (n) through Which (5) Threads of micorhiza (i») making their 



they make their entrance, (/) triangular way in between the epidermis cells (t) 



patch bearing the food bodies. of a root. 



(2) Section of a lichen showing the algal (fi) Root of a leguminous plant with root 



cells ((() which are surrounded by the tubercules. 



threads of the fungus (/). (7) Bacteroids from a root-tubercle. 



(3) Fungal threads of a lichen (/) capturing (8) Bacterium vermiforme of the ginger- 



algal cells (a) for the formation of a beer plant. 



new lichen-cell. (0) Saccharomyces pyiiformis of the giuger- 



(2 and 3) After Sachs. beer plant. 



