SYMBIOSIS IN A DECIDUOUS FOREST. I 
W B. McDovUGALL 
(WITH THREE FIGURES) 
Introduction 
In a previous paper’ symbiosis is defined as the living together 
of dissimilar organisms, and the phenomena of symbiosis are 
classified as follows: 
I. Disjunctive symbiosis II. Conjunctive symbiosis 
1. Social 1. Socia 
2. Nut 2. Nutritive 
a. Antagonistic a. Antagonistic 
b. Reciprocal b. Reciprocal 
The writer has felt for some time that there is urgent need of 
work along the lines of these various types of symbiosis. Consider- 
able work has been done on the relations of plants to their physical 
environment, but the work done on their relation to the biotic 
environment has not been in proportion to the importance of this 
phase of ecology. 
Some five years ago the University of Illinois obtained possession 
of a sixty acre tract of forest. This land is located about five miles 
northeast of the University in Champaign County, Illinois, and 
is a remnant of a former much more extensive forest. It is known 
as the ‘University woods.” Many of the primitive trees are still 
standing in this tract, although some cutting has been done in the 
past, and the forest was frequently pastured before it was acquired 
by the University. It may be said, therefore, to be only semi- 
primitive. It has been stated that there is very little if any natural 
forest vegetation in the state of Illinois at the present time, but the 
use of the word natural in such a statement is ill chosen and makes 
the statement inexact. It is true that there is very little if any 
such vegetation that has not been modified to a greater or less extent 
by man. Vegetation that has been influenced by man, however, is 
? McDoveatt, W. B., The classification of symbiotic phenomena. Plant World 
212250-256. 1918. 
Botanical Gazette, vol. 73] [200 
