462 Mr. W. Stiles and Dr. F. Kidd. Position of the 



Later work by the same author, conducted on similar lines with slices of 

 Dahlia tuber (7), and of beetroot and Helianthus tuber (8), show that with a 

 variety of salts used in strong concentration the tissue never takes up the 

 quantity of salt necessary for equality of concentration in the tissue and in 

 the external liquid. This research contains further certain interesting indica- 

 tions that the absorption ratio varies in the manner shown by our experiments 

 as described above. In a series of comparable experiments with Dahlia slices 

 the following figures were obtained : — 



Table IX. — Absorption Eatios with Dahlia. (Data from Nathansohn.) 



Salt. 



External concentration. 



Time. 



Absorption ratio (kation). 





per cent. 



days. 





NH.NO, 



1 -5 



4 



0-32 



0-5 



4 



0-53 





1 -0 



2 



0-63 





0-5 



1 



0-98 



:N'aXO., 



1 -0 



6 



0-51 





0-5 



5 



0-94 





1 -0 



4 



0-69 





O-o 



4 



1 -05 



These results of Xathansohn's, although the author himself did not draw 

 the conclusion, clearly show that the absorption ratio depends upon the 

 external concentration in the manner indicated by our experiments, namely, 

 that there is a rapid rise in the ratio as the external concentration of the 

 absorbed salt is increased. 



Nathansohn's work was later extended by Meurer (3), who used discs of 

 beetroot and of carrot 3 mm. in thickness, immersed in a variety of solutions, 

 The intake of salt, or rather of ions, was measured by the change in concen- 

 tration of the external solution as determined by direct chemical analysis. 

 Meurer's results confirmed those of jSTathansohn in resjard to the fact that 

 equality of concentration was never reached. We may quote Meurer's figures 

 obtained with carrot for comparison with those recorded in this paper for the 

 same tissues. His results with beet are parallel. 



It will be observed that in all cases the individual ions of the salt have not 

 been absorbed to the extent required for equal distribution, even after four 

 days, the absorption ratios being for the most part less than 0"5. 



As in our experiments, Meurer also compared living and dead tissue. 

 His results, quoted below, are the same as ours. He found that in the case 

 of dead tissue the absorption ratio for both ions was approximately unity 

 (actually slightly less). The failure to reach a condition of equal salt 



