166 Physiologie. 



BayJiss, W. M., On some aspects of Adsorption Phenomena 

 with especial reference to the action of Electrolytes and 

 to the Ash-constituents of Proteins. (Biochemical Journal. Vol T. 

 Nos. 4 and 5. 1906. p. 175—232.) 



It is very difficult to prepare proteins free from salts. A certain 

 amount can be readily removed by dialysis but beyond a certain 

 limit it is a matter of very prolonged labour to get rid of the 

 remaining small amount. It has been shown that from a Solution 

 filterpaper will adsorb a dye in relatively larger proportion the 

 more dilute the Solution. Experiments with gelatine have shown that 

 repeated treatment with water extracts successively smaller and 

 smaller quantities of salts, the resulting curve being hyperbolic 

 while the curve of electrical conductivety of successive extracts has 

 the same form. It is impossible to wash out all the electrolytes from 

 gelatine except by a practically infinite number of changes of water. 



The electrolytes are neither chemically united nor mechanically 

 held but adsorbed. 



Gelatine washed nearly free from electroU'tes diminishes the 

 conductivety of an electrolytic Solution by adsorbing the electrolytes 

 in a non-ionized condition. Rate of adsorption is, in some cases at 

 least, increased by rise of temperature, but the total amount 

 adsorbed is diminished. Equilibrium between adsorber and adsurbed 

 material is only attained slowly at low temperatures. With increased 

 temperature the adsorption Compound of gelatine and electrolyte 

 becomes dissociated. No evidence of any rise of temperature" during 

 adsorption was found. The adsorption reactions are reversible. 



In the case of an electronegetative dye, kations facilitate adsorption, 

 anions depress it. In the case of electropositive dyes, anions facilitate, 

 kations depress adsorption , but in both cases the action of the kation 

 is much greater than that of the anion. The effect of bivalent 

 kation is greater than twice that of Univalent ones. Salts of the 

 heavy metals which form positively charged colloidal Solutions have 

 a powerful effect in promoting adsorption of electronegative dyes. 



When gelatine is precipitated bj'- tannin , its adsorbed electrolytes 

 are split off. There is no evidence of a sudden liberation of electrolytes 

 at death. There is a gradual liberation as the temperature is raised. 



The nature of the Compounds between acid and basic dyes is 

 investigated. They appear to be unchanged colloids, but it is impossible 

 to say whether they are colloidal adsorption Compounds or true 

 Chemical Compounds. There is evidence that the union between 

 enzyme and substratum (colloidal) is of the nature of adsorption. 



E. Drabble (Liverpool.) 



Czapek, Friedrieh. Oxydative Stoffwechselvorgänge bei 

 pflanzlichen Reizreaktionen. I. Abhandlung. (Jahrb. für 

 wissenschaftl. Botanik. XLIII. p. 361—418. 1906). 



Die Arbeit ist eine Fortsetzung der Untersuchungen desselben 

 Verfassers aus den Jahren 1897 u. 98 (Berichte der Deutsch, bot. 

 Ges. und Jahrb. f. w. Botan). Es wird von neuem gezeigt, dass in allen 

 Wurzelspitzen stark reduzierende Stoffe auftreten, die vornehmlich 

 als oxydative Abbauprodukte des Tyrosins zu betrachten sind. Den 

 Hauptanteil an diesen Stoffen hat wahrscheinlich die Homogenti- 

 sinsäure. Doch betont Verf. ausdrücklich, dass der exakte analytische 

 Nachweis für das Vorkommen dieser Säure noch zu erbringen ist. 



