1907] 



OSTERHOUT— BALANCED SOLUTIONS 



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TABLE IX. SECTIONS 



All quantities given are cubic centimeters of 3W/32 solutions. 



Culture Solution 



Dilute artificial sea water: 

 1000 NaCl 



73 MgCl. 



38 MgS04 



22 KCl 



10 CaCI, 

 Distilled water 



NaCl...., 

 1000 NaCl I 



10 CaCIa 3 



1000 NaCl 

 22 KCl 

 10 CaCla 



Duration of Life in Days 



Red beet: 



Cross-sections 



of root 



35 



35 

 18 



25 



Mesembry- 

 anthemum : 



Cross- sections 

 of leaf 



Tradescantia: 



Cross sections 



of stem 



Tropacolum: 



Cross sections 



of leaf 



16 



30 



l8 



9 



12 



19 



15 



20 

 12 



18 



19 



25 



32 

 20 



22 



For the sake of clearness it seems desirable to call attention to the 

 distinction between balanced solutions and ordinary nutrient solu- 

 tions. A nutrient solution may be used in such dilute form that none 

 of its components could exert any toxic action even if the other con- 



stituents were removed. 



poisonous 



to be inhibited and consequently no balancing of the solution is 

 required. Our only concern is to supply all the substances needed 

 for nutrition, irrespective of any balancing action, and so form a 

 complete nutrient solution. 



If we increase the concentration of this solution, however, we soon 

 reach the point where some or all of the components begin to exert 

 their individual toxic effects, whereupon it may become necessary 

 to inhibit these effects by proper adjustment of the relative propor- 

 tions of the substances present or by the addition of other substances. 

 The substances added to produce a balance do not necessarily have a 

 nutritive value. For example, Loeb^ was able to balance certain 

 solutions by adding zinc, cobalt, aluminum, etc.^ 



5 Am. Jour. Physiology 6:411-433. 1902. 



* To make clear this distinction between balanced and nutrient solutions is more 

 necessary, since Loew^ and Aso (Bull. Coll. Agr. Tokyo Imp. University 7^^395- ^9^l) 

 confuse the two kinds of solutions. Their criticisms are wholly based on this mis- 

 conception and do not affect the matter as T have presented it. The distinction 

 between nutrient and balanced solutions is due to Loeb, who has explained it clearly 

 in his Dynamik der Lebenserscheinimgen 1 15-120. 



