I12 SCHAFFNER: SEXUAL STATE IN SAGITTARIA LATIFOLIA 
organism appear to be conditioned on the interaction of four 
fundamental causes: 
The presence of hereditary factors in the protoplast, 
apparently properties of the chromosomes. This is, of course, 
the fundamental influence or cause. 
2. The influence of environment, both external and internal, 
giving rise to fluctuations, often resulting in very great mor- 
phological and physiological differences. 
3. The progression of senility or rejuvenation which often 
has a decided effect on the hereditary expression. 
. The presence or absence of sexual states in the living sub- 
stance through which primary and secondary sexual characters 
or dimorphisms are produced without a change in genotype. 
In so far as the evidence goes, the observed conditions of the 
monecious state in Sagittaria are in entire agreement with these 
conclusions. 
OHIO STATE UNIVERSITY. 
