418 GROWTH OF PLANTS 



concentrations of copper salts for potato tissue and of copper salts and LaCls 

 for rye seeds reduced the pH to 3, far below any value that is claimed for 

 the plant protems of these plant organs. 



Salt solutions are similarly acidified when water extracts of plant tissue 

 are added to them; and this occurs even when the extracts are boiled or 

 dialyzed to precipitate proteins and remove all colloids from the extracts. 

 When salts were added to organic acid solutions (malice, oxalic, succinic, 

 aspartic, etc.) there is an increase in hydrogen-ion. Additions of CaCl2 to 

 salts of organic acids increased the acidity in all pH values from 2 to 7.5. 

 The increase in hydrogen-ion appears whether the salts of the organic 

 acid were or were not precipitated. Additions of CaCl2 to phosphates and 

 pectin increased the hydrogen-ion. The addition of CaCl2 to that portion 

 of potato extract containing the protem tuberin shows that the change in 

 hydrogen-ion is not analogous to the change caused by addition of potato 



tissues. 



From a consideration of the results of all their experiments, the authors 



draw the following conclusions : ''- ^■'''- ^'^ ""'' ^° ^- ^- '"■'■■ 



"Although our results do not show that the tissue itself or the proteins 

 take no part whatever m these changes m pH, they indicate that the solu- 

 ble, non-protein, non-colloidal substances which diffuse out of the tissue 

 into the salt solution and which then react with it are important factors in 

 the acidifications that are produced in the external solution. 



"The observed changes in hydrogen-ion concentration, therefore, can 

 not be interpreted as indicating an isoelectric point for the tissue as a whole, 

 nor furnish proof that reaction has occurred between the ions of the salt 

 solution and proteins with characteristic isoelectric points." 



Growth Substances and Vitamin Bi for Seed Treatment 



One commercial firm has been vigorously promoting the use of plant 

 hormones for seed treatment, claiming that the treatment greatly mcreases 

 crop yield. Investigators at this Institute and most, though not all, of 

 many investigators of the subject elsewhere have found no advantage in 

 hormone treatment of seeds. 



Barton ^ soaked non-dormant seeds of twenty-nine different species and 

 varieties of farm, garden, and flowering plants and grasses in a wide range 

 of concentrations (320.0 to 1.2 mg per liter of water) of three different 

 growth substances (|3-indoleacetic, /3-indolebutyric, and o;-naphthalene- 

 acetic acids) and grew them to maturity in soil. Except for higher concen- 

 trations which ui some cases inhibit growth or cause malformations, the 

 treatments had no effects, either on germination or final yield. She also 

 treated seeds with several proprietary plant hormone preparations, mainly 

 talc dust mixtures, with similar results. 



Dormant American elm seeds i" soaked in various concentrations of 

 potassium a-naphthaleneacetate showed some improvement in germina- 



