419] W. #£. Tottingham 221 
ing effect of chlorine, as reported? for starch content and 
cooking quality of potato tubers, does not obtain under all 
conditions of culture, and fails to make itself manifest with 
the climatic and soil conditions of these experiments. 
The results outlined above leave the question of the in- 
fluence of the chlorine ion and chlorides upon plants still in 
a very complicated and unsatisfactory condition. Perhaps 
the most valuable general conclusion that can be drawn from 
a review of all the work so far reported upon this subject, is 
that the influence here considered appears to be impossible 
of any general statement. It appears that the effect of 
chlorine upon any given plant depends upon the nature of 
the plant, upon the soil conditions (aside from chloride con- 
tent) and upon the conditions of the surroundings generally 
classed as climatic. It may be that each particular case of 
acceleration or retardation of growth processes by chlorine 
presents a special problem, and that broad generalizations 
are not to be expected until much progress has been made 
toward the interpretation of environmental complexes as a 
whole; for the present, we are constrained to study these con- 
ditions piecemeal. It seems that the promise of progress in 
these very complicated problems of agricultural science lies 
largely in more complete experimental control of the very 
numerous conditions that make up the environment of the 
plant. It is the summed or integrated effects of all of these 
that is registered by our plants in growth and crop produc- 
tion. 
2 For example, see: Stichting, H., “ Ueber die schidigende Wirkung 
der Kalirohsalze auf die Kartoffel.”” Landw. Versuchsst. 61: 397- 
449. 1905. 
