52 Hydration and Growth. 



range of conditions than those presented by the swelling of simple 

 gelatine in electrolytes, especially at uncontrolled or unrecorded tem- 

 peratures. 



Professor F. E. Lloyd, working under the equable temperature con- 

 ditions of the Coastal Laboratory at Carmel, CaUfornia, measured 

 the growth of pollen-tubes of Phaseolus odoratus in acids (hydro- 

 chloric, acetic, malic, citric, formic, and oxalic) at concentrations 

 N/200 to N/25,600 in association with cane sugar in concentration 

 of 40 per cent. In these solutions no growth occurs at concentra- 

 tions at or above N/3,200 of the acid component. Below that limit 

 the rate of growth is inversely as the concentration. The rate and 

 total amount of growth possible for any concentration varied with 

 the acid, it being least at the higher concentrations for formic and 

 oxalic and highest for acetic.^ 



No temperature records are cited in any of these cases or in the other 

 work described by Long or Dachnowski. 



The measurements of E. R. Long brought out the fact that growth 

 in Opuntia was greater in culture salt solutions than in any other 

 medium tested, while that in alkaline solution was more than in either 

 malic or hydrochloric acid, these substances being used in concentra- 

 tions of N/50, while the solutions of Borowikow were N/100 or weaker.^ 



A. Dachnowski measured the swelling and water-relations of seeds 

 of beans and com and cuttings of tomato shoots and obtained some 

 facts of great interest.^ Beans were found to absorb and retain less 

 water in acid solutions (N/800) than in equi-normal alkaline solutions. 

 The cations Ca and Na were more active than potassium in limiting 

 imbibition in beans, a relation which is reversed in com grains, in 

 which the greatest swelling took place in calcium, a lesser amount in 

 potassium, and a minimum in sodium. Cuttings of tomato plants 

 were found to function better in an alkaline medium than an acid, and 

 best of all in water in absorption and transpiration. Sulphuric acid 

 at N/3,200 and potassium hydroxid at N/6,400 furnished exceptions to 

 these conclusions. The effect of any salt on the water-relations of the 

 plants used was the sum of the constituent ions, a conclusion confirm- 

 ing the work of Borowikow. 



The well-known cultural conditions required by many bacteria and 

 fungi furnish still further exemplification of the diversity of behavior 

 of the biocoUoids in the hydration necessary for growth. The plasma 

 of bacteria is high in albumin and many bacteria show the highest 

 velocity and greatest development in a medium containing the soluble 

 proteins combined with sodium chloride and brought to an alkaUne 



^ Lloyd, F. E. Collodial phenomena in the protoplasm of pollen tubes. Rept. Dept. Bot* 

 Res., Year Book Carnegie Inst. Wash., 1917, p. 63. 



* Long, E. R. Growth and colloid hydratation in cacti. Bot. Gazette, 59: 491. 1915. 



* Dachnowski, A. The effects of acid and alkaline solutions upon the water-relations and the 

 metabolism of plants. Amer. Jour. Bot., 1: 412-439. 1914. 



