604 Physiologie. 



frei. Dieses wird sodann von den grünen Pflanzen wieder zerlegt, der 

 Kohlenstoff wird assimiliert. Von den Lebewesen wird er als Koh- 

 lehydrat oder als Eiweis wieder aufgenommen. 



W. Herter (Tegel). 



Transeau, E. N., Apparatus for the study of comparative 

 transpiration. (Bot. Gaz. LH. p. 54 — 60. flg. 1 — 5. July, 1911.) 



Essentially a modification of Ganong's transpirograph developed 

 for comparative work. The complete outfit consists of a hygrother- 

 mograph, a Chronograph, chemical balances, weight droppers, and 

 irrigators. The Chronograph/ weight droppers and irrigators are new 

 forms of wellknown devices. Moore. 



True, R. H. and H. H. Bartlett. Absorption and excretion 

 of salts by roots, as influenced by concentration and 

 composition of culture Solutions. I. Concentration regu- 

 lations of dilute Solutions of calcium and magnesium ni- 

 trate to pea roots. (U. S. Dept. Agric. , Bur. Plant Ind., Bull. 

 CCXXXI. p. 1—36. flg. 1-21. Jan. 20. 1912.) 



The results of a series of experiments vvith Canada field peas 

 grown in Solutions of calcium and magnesium nitrates. The culture 

 methods, which are described in detail, were designed especially 

 io deal with the high dilutions used and to prevent error. Prelimi- 

 nary experiments calculated to indicate the specific reactions of pea 

 roots to Solutions of magnesium and calcium nitrate, were followed 

 by a series in which the conductivity of the culture Solutions are 

 determined by the wheatstone bridge, the results of which are given. 

 From these experiments it is concluded; 1) that there is a definite 

 concentration for each salt or mixture of salts at which the roots 

 of peas absorb and excrete electrolytes at the same rate; 2) that if 

 a culture Solution is initially less concentrated than this equilibrium 

 concentration, excretion from the roots over balances absorption; 

 3) that if a Solution is initially more concentrated than this equili- 

 brium, absorption over balances excretion; 4) that absorption from 

 Solutions initially above equilibrium concentration may carry them 

 far below this concentration; 5) that the extent to which pea roots 

 can carry the concentration of a Solution below equilibrium concen- 

 tration depends upon the ratio of magnesium to calcium; 6) that the 

 molecular ratio which favors maximum absorption is £; 7) that the 

 ratio of magnesium to calcium which insures good development of 

 pea roots is f , if the Solutions are so concentrated that their magne- 

 sium content alone would inhibit the development of lateral roots; 

 but 8) that this ratio is nearer — if the Solutions are so dilute that 

 the magnesium content alone would not inhibit the development of 

 lateral roots. Moore. 



Zeeuw, R. de, The comparitive viability of seeds, fungi 

 and bacteria when subjected to various chemical 

 agents. (Cbl. f. Bakt. 2. Abt. XXXI. p. 4—23. 1 flg. 1911.) 



Verf. bespricht zunächst die von früheren Autoren angestellten 

 Versuche, Samen von Krankheitskeimen zu befreien. Sodann macht 

 er ausführliche Angaben über die den eigenen Experimenten zu- 

 grunde liegende Technik. 



Er operierte mit folgenden Reagentien: Schwefelsaure mit Ka- 



