iQig] 



HOAGLAND—CELL SAP OF BARLEY 



299 



definite relationship is apparent. The highest osmotic pressure 

 is found in the sap from the plants grown in the acid nutrient 

 solution of highest concentration (1.72 atmospheres). The roots 

 of these plants showed marked evidence of injury. In all cases 



TABLE I 



Osmotic pressure, conductivity, and H ion concentration of 

 plant sap in water, sand, and soil cultures 



Total 

 solids 

 approxi- 

 mate 

 p.p.m. 



200 

 200 

 1400 

 1300 

 2300 

 2200 

 4500 

 4300 



2500 

 5000 

 8000 



600 

 600 

 900 

 500 

 500 

 200 



Nutrient solution 



3 o 



;■§. 



v 

 o 



Sis °. 



o. 

 m 





Plant sap from tops 



3 S 

 t« C il 



t-3 ai 



a' 



C/2 



c . a 



O r!CL 



c = § 



Pl.\nt sap from roots 



w i/i £ t- 



o u i: Si 



aS-g. 



^ 'Si 



Q. 



g.2 



Barley plants 8 weeks, grown in water cultures 



0.07 

 0.07 

 0.58 

 0.56 

 0.88 

 0.88 

 1.72 

 1 . 70 



3870 



3230 

 550 

 528 



347 

 347 

 196 

 189 



•50 



■53 

 .48 



■83 

 ■14 

 .76 



•94 

 •14 



8.01 



7-55 



8.13 



8.35 



8.86 



10.26 



II .40 



10. 24 



97 

 76 

 61 

 66 

 65 

 50 

 53 

 S3 



68 

 6« 



85 

 82 



99 

 90 



95 

 90 



62 

 69 

 II 



04 



52 

 90 



63 



125 

 137 

 117 



102 



119 



95 



77 



6.44 

 6. 12 



6.83 



6.97 

 7.08 



6.97 



Barley plants 7 weeks, grown in sand cultures 



0.94 

 1. 81 

 2-75 



Barley plants 6-7 weeks, grown in 6 diferent soils 



0.22" 



0.2I 



0-33 

 o. 16 

 o. 19 



0.08 



96 



52 



96 



14 



97 

 II 



59-9 

 60.4 

 64.2 

 69.2 



715 

 65.8 



of 

 6.12 



6.15 

 ot 



5-99 

 6. 12 



* This column represents concentration of soil solution at about time plants were collected; pre- 

 viously the concentration was higher, 

 t No determination was made. 



the osmotic pressure of the tops is much greater than that of the 

 corresponding roots. These findings are in general agreement 

 with those of McCool and Millar. The tops of the plants 

 grown in the various soils have osmotic pressures similar to those 

 found in the water culture experunents. The osmotic pressures 

 of the soil solutions, as determined by the method of Bouyoucos 

 and McCooL, varied between 0.08 and 0.33 atmospheres at 



