iQoS] OSTERHOUT— ACTION OF MAGNESIUM AND POTASSIUM 123 



stems) 



seemed 



stems 



behave in the solutions. The answer to this question is given in 

 Table VH. Transverse sections of the stem of Tradescantia and the 

 root of the common red beet were employed. They were cut on a 

 microtome and were of considerable but uniform thickness. 



TABLE VII 

 Cuttings and Sections 



All quantities given are cubic centimeters of .0937m solutions 



CULTTRE SOLUTION 



Duration of life dj days 



Microtome sections 



of stem of 

 Tropaeolum majus 



KCl 



100 KCl 

 40 MgCU 



MgCl. 



Distilled water 



20, 

 28 + 



20 

 28 -f 



Microtome sections 



of root of 



Beta vulgaris 



Development 



Cutting i5«" 



long of 

 Tradescantia 



14 



18 



28 + 



No roots 

 Short roots 



No roots 

 Long roots 



A plus sign indicates that the plants were alive at the end of the experiment. 



In both cases the color and microscopic appearance served as the 

 criterion of death. As is seen in Table VII, the results agree with 

 those already obtained. The table Ukewise shows the results obtained 

 from cuttings of Tradescantia (about 15*=^ long) which were placed 

 with then: lower ends in the solutions. 



obtam 



variety of material, it seems useless to seek for furtter proof. 



The 



leriments 



slum and magnesium, as far as they go. They do not, however, 

 emplov sufficient potassium (nor sufficiently strong solutions ) to bring 

 out the results clearly. The use of percentage solutions (rather 

 than molecular solutions) likewise obscures their results. More funda- 

 mental is their confusion of physiologicaUy balanced solutions with 



ordinar}' nutrient solutions.' 



As for the theorj- of LoEW and Aso that the mhibitorj- action of 

 potassium on magnesium is due to the formation of a double salt, I 



s Cf OSTERHOUT, On nutrient aed balanced solutions. University of Calift^a 

 PubUcations.Botany2:.U7. iW! also. Box. Gazette 44 : ^59-272- i9°7- 



