1918] Waynick: Antagonism and Cell Permeability 155 



Several cultures in which mercuric chloride was used and in which 

 growth was good, displayed the same dark green color as noted for 

 copper salts and the same suggestion as made for the Functioning of 

 copper in this color relationship may hold for mercuric salts as well 

 in very dilute solutions. 



The color was light green when iron salts were present ; with the 

 other salts used no marked external effects were noted. 



General Review of Experimental Results 



It seems advisable to consider the results reported in the previous 

 tables together, so that the data presented in one table may be more 

 closely correlated with those given in another. It is proposed to do 

 this in the present section and further to discuss briefly the more 

 important relationships shown. 



It will be noted in the accompanying tables that there is consid- 

 erable variation between the controls grown at different seasons of 

 the year. This was to be expected, since conditions in the green- 

 house varied between the different growing periods. For this reason 

 it is not possible to compare one series of cultures with another so 

 far as absolute weights of the dry matter are concerned. Within any 

 one series or between series grown at the same time the absolute 

 weights are comparable. This point must be borne in mind in con- 

 sidering the results as a whole. In some cultures, however, growth 

 was stimulated to such an extent as to far surpass any variation 

 between series due to differing external conditions. Such a case is 

 that of series 22. in which ferric sulphate was added to the nutrient 

 solution in varying amounts. In culture 5 of this series, the dry 

 weight was over twice that of any control plants grown during the 

 entire time. 



The experimental work with the salts of calcium plus magnesium 

 was rather extensive. McCooP 2 has reviewed the previous work with 

 calcium and magnesium salts as related to plants, so a discussion of 

 that phase of the relationships between the two need not he entered 

 into here. In his own work McCool found that calcium chloride wai 

 effective in antagonizing the poisonous effects of magnesium chloride 

 and magnesium sulphate. He found a slight increase in the growth 

 of pea seedlings over the controls based upon the ureen weight of the 

 plants. This was the case in distilled water and in nutrient solution. 

 It seems probable that the nutrient solution used by .McCool was not 



32 Cornell Univ. Ajjr. Exp. Sta. Mem. 2 (1913), p. 12'.». 



