^ 



VOLUME XXXIV 



NUMBER 2 



Botanic Ai 



Gazette 



AUGUST, igo2 



THE 



JUICES 



Fred. D. Heald. 



(with two figures) 



<< 



the 



VVjth the recent rapid development of physical chemistry, 

 the physiologist has recognized the fact that the application of 

 the methods of physical chemistr}' to problems of plant physi- 

 ology is highly important. Already fruitful results have been 

 obtained in a number of lines, and it only remains for future 

 investigations to increase and supplement them. Since 

 conductivity of electrolytic solutions stands in direct relation- 

 ship with certain phenomena," particularly with the osmotic 

 pressure and with the depression of the freezing-point, it has 

 seemed possible that the determination of the electrical con- 

 ductivity of plant juices, which are themselves electrolytes, might 

 yield interesting results. Some determinations of this character 

 have been carried out, and although the results are not all that 

 might be expected, they are, to say the least, promising, and 

 willjje recorded in the following pages. 



conductivity of electrolytes has been an especially prom- 

 inent subject in the investigations of physical chemistry, so much 

 so that it may almost be called the Leitmotiv. The methods of 



investigations and the principles established have recently 

 found application outside the province of physical chemistry. A 

 number of instances may be mentioned. The Division of Soils, 

 ^- S. Department of Agriculture, has used the electrical con- 

 ductivity methods for determining the moisture content^ of 



Th 



thes 



e 



' Bulletin no. 6 ; also 



no. 12. 



8i 



'\ 



