419] W. E. Tottingham 221 



ing effect of chlorine, as reported 2 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: Siichting, H., " Ueber die schadigende Wirkung 

 der Kalirohsalze auf die Kartoffel." Lcmdw. Versuchsst. 61: 397- 

 449. 1905. 



