February 20, 1914] 



SCIENCE 



293 



Differential Permeability : W. J. V. Osterhout. 



Various kinds of surfaces in the cell, such as 

 the outer "plasma membrane," the vacuole-wall, 

 the nuclear wall, the surface of the chromatophore 

 and the cell wall can be proved to differ greatly in 

 their behavior with respect to permeability. 



The term differential permeability may be sug- 

 gested as an appropriate designation of these phe- 

 nomena. 



The Effect of Antagonistic or Balanced SolutioJis 

 Containing Sodinm Chloride together loith One 

 of the Chlorides of Calcium, Magnesium, Po- 

 tassium, Strontium, Ammonium or Copper, upon 

 the Growth of Corn Plants Hooted in an Arti- 

 ficial Soil: Joseph S. Caldwell. 

 The primary purpose of the work was to deter- 

 mine in how far the use of a solid medium having 

 known physical properties may modify the antag- 

 onistic relationships borne by sodium to each of 

 the other ions named. 



For each of the six pairs of salts, cultures were 

 grown in finely divided quartz to which the salt 

 mixtures were added, the optimum water content 

 for the quartz being maintained constantly through- 

 out the experiment. For each pair of salts, ten to 

 twenty different concentrations were used, the low- 

 est of such concentration as to totally inhibit de- 

 velopment, the last so dilute as to be entirely with- 

 out effect upon the plants. For each of these con- 

 centrations, a series of cultures consisting of 

 twelve to sixteen mixtures of the two salts in pro- 

 portions ranging from 60 : 1 to 1:60 was made, 

 with check cultures in each of the pure salts. The 

 complete series for any pair of salts, therefore, 

 shows for each salt the range of inhibitory, toxic 

 and stimulatory effects, for comparison with the 

 effects of isosmotio mixtures in varying propor- 

 tions with the opposing salt. In all cases, results 

 are measured by comparison of the dry weights of 

 roots and tops, taken separately, for cultures al- 

 lowed to grow under controlled conditions for 30 

 days. 



Antagonism between sodium and strontium mani- 

 fests itself at aU molecular ratios between Sr 1 : 

 Na 10 and Sr 1: Na 20, and in all concentrations 

 between those just permitting measurable develop- 

 ment and those too dilute to have discoverable ef- 

 fect, but manifests itself only through its effect 

 upon root development. 



The effect of additions of calcium to sodium is 

 merely to decrease the characteristic physiological 

 and morphological effects of sodium in a degree 

 directly proportional to the amount added, but in 



no case can these characteristic effects be made 

 entirely to disappear. The effect of calcium is a 

 dilution effect and not an antagonistic one. 



In mixtures of copper and sodium, sodium 

 serves merely to dilute the copper salt, decreasing 

 the toxic or the stimulatory effect in direct pro- 

 portion to the amount added, but in no case an- 

 nulling the effects of the copper ion. 



Additions of magnesium to sodium in any pro- 

 portions or at any concentration is without effect 

 upon the development of aerial parts. In highly 

 toxic concentrations, mixtures in the ratio of 

 Mg 2: Na 1 give somewhat better development of 

 roots, while in all stimulatory concentrations the 

 ratio 1: 1 gives greatest dry weight for roots. 

 Mixtures of sodium and potassium inhibit develop- 

 ment of both roots and tops, in all inhibitory or 

 toxic concentrations, to a markedly greater extent 

 than do isosmotic solutions of the pure salts. In 

 stimulatory concentrations, the pure salts permit 

 greater and more normal development than do mix- 

 tures. Sodium in any proportion, even in concen- 

 trations at which it is markedly stimulatory, de- 

 creases the stimulatory effect of potassium. 



For mixtures of sodium with ammonium, highly 

 toxic concentrations permit slightly greater de- 

 velopment when the two ions are present in the 

 ratio 1:1. For all stimulatory concentrations, the 

 stimulatory effect is decreased in mixtures, growth 

 becoming better as the ratio of one ion to the 

 other increases from 3:1 to 60: 1. 



Metabolic Changes in Potato Tubers Diiring 



Sprouting: Chas. O. Appleman. 



The following metabolic changes occurred during 

 the early stages of sprouting: (1) Under constant 

 storage temperature the starch was depleted, while 

 the reducing sugars showed a slight increase. The 

 above carbohydrate changes were more rapid in the 

 stem end. (2) Both diastase and invertase activ- 

 ity of the glycerine extract quickly doubled; the 

 increase was greater in both cases in the extract 

 from the stem half. (3) Catalase showed a marked 

 increase which was slightly greater in the juice 

 from the seed end where it was more active before 

 sprouting. (4) The nitrogen of monamino -acids 

 and their amide derivatives increased, while the 

 nitrogen of diamino-acids and other organic bases 

 and the water-insoluble protein nitrogen decreased. 

 The abundant water-soluble protein nitrogen in 

 the tubers showed a very slight increase. (5) Or- 

 ganic extractive and lipoid phosphorus increase at 

 the expense of protein and inorganic phosphorus. 



