270 



BOTANICAL GAZETTE 



[OCTOBER 



in the solution. Absorbent cotton was packed in the neck of the 

 bottle to exclude dirt and hinder evaporation. The results were 

 similar to those described above, as will be seen from Table VIII. 



Finally the question was raised whether 

 the tissues of the stem and leaf, if brought 

 into direct contact with the solution, would 

 behave like the root. To 

 answer this, sections of 

 considerable (but uni- 

 form) thickness were cut 

 with a microtome and 

 placed in the solutions. 

 The results appear in 

 Table IX. 



The results described 

 in this paper are in all 

 essentials in striking 

 agreement with those 

 obtained from the study 

 of marine plants, as well 

 as from the study of 

 marine and fresh-water 

 animals as referred to in 

 the first part of this 

 paper. This agreement 

 shows that the principle 

 of balanced solutions is 

 of general validity. 3 The 

 application of this prin- 

 ciple to soil and river water 4 and to nutrient solutions, I hope to take 

 up in a subsequent paper. 



3 LOEW and his pupils have shown that calcium antagonizes magnesium (cf. 

 Bull. No. 18, Div. Veg. Phys. and Path. U. S. Dept. Agric. 1899). See also the antago- 

 nistic effects noted by KEARNEY and CAMERON (Report No. 71, U. S. Dept. Agric. 

 1902) in their studies on the salts of alkali soils. The method employed by them 

 (observation of the root-tip only) is so different from mine that I have not attempted 

 to compare the results. 



4 In the first part of this paper I have referred to the composition of tap water, 

 but it seems advisable to defer the discussion of this point. 



FIG. 7. Growth of roots of wheat for 40 days. 

 I, in dilute artificial sea water (NaCl = ap. 3^/25), 

 aggregate length of roots 360""". 2, in distilled 

 water, aggregate length of roots 74o mm . 



