374 Physiologie. 



Ernest, A., Beitrag zu der Methodik der Erforschung 

 des Atmens der Wurzeln. (Vestnik V. sjez. ces. prir. p. 431. 

 1915.) 



Um zu konstatieren, ob event. Bakterien auf die Bildung von 

 CO2 nicht eine Wirkung ausüben, hat Verf. eine Kontroimessung auf 

 besondere Art und Weise in den Versuch eingeführt, die die CO2- 

 Mengen praecis zu bestimmen erlaubt. Die Methode mit zugehöriger 

 mathematischer Formel ist im Original nachzulesen. 



Jar. Stuchlik. 



Fischer, M. H. and A. Sykes, Non electrolytes and the 

 colloid-chemical theory of water absorption. (Science 

 N. S. XXXVIII. p. 486-487, 1913.) 



Salts reduce the hydration of fibrin and gelatine by acids but 

 do not afifect the increased hydration induced through urea. Non 

 electrolytes affect but little the hydration brought about by acids 

 but reduce almost entirely the hydration produced by urea. 



W. H. Emig (St. Louis). 



Füller, G, D., Germination and growth ofthecotton-wood 

 upon the sand d unes of Lake Michigan near Ch icago. 

 (Trans. 111. Acad. Sei. V. p. 137-143. fig. 1—6. 1912.) 



The studies reported in this paper were made from May Ist to 

 Oct. 31, 1911, on a sand dune and its characteristic plants near 

 Chicago. Weekly evaporation determinations by the Livingston 

 atmometer showed rather excessive xerophytic conditions (24.6 c. c. 

 evaporation per da}^ as compared to 8 c. c. per day in a beech-maple 

 forest). The soil-moisture determined weekly for the same period 

 showed, however, that there was always some water present in the 

 soil over and above the percentageindicated by Briggs and Shantz 

 as the wilting coefificient. This moisture the author has termed 

 "growth water". The first dune tree in that region is Populns 

 deltoides. As it cannot propagate by seeds, because of the instability 

 of the subStratum, it does so vegetatively by sending out adven- 

 titious roots as the trunk and branches become covered by sand, 

 and by sending out adventitious shoots from the roots as these are 

 exposed. Going further back in time, the seedlings of this tree 

 first become established in the dune region by the germination of 

 seeds in moist depressions or "pannes". M. C. Merrill (St. Louis). 



Harvey, E. N., A criticism of the indicator method of 

 determining cell permeability for alkalies. (Amer. 

 Journ. Physiol. XXXI. p. 335—342. 1913 ) 



Because the indicator is contained in the cell in some sort of 

 Chemical combination, adsorption, or absorption, and because there 

 are present proteins or other substances which might influence the 

 color change, criticism has been made against it. The present paper 

 is a consideration of the objections against the method. A strong 

 alkali (NaOHj and a weak alkali (NH4OH) were used and observations 

 were made regarding their penetration into living plant and in animal 

 cells, artificial cells, and dead cells. Some of the results or conclusions 

 are: the normal plasma membrane is impermeable to NaOH while 

 NH4OH readily penetrates it; NaOH enters only after changing the 



