Pflanzenchemie. 573 



5, Washing does not affect the activity of the catalase of 

 dried yeast. 



6. The power of hydrolysing cane sugar is partially, but not 

 entirely, removed from zymin and dried Mu ni ch yeast by repeated 

 washings at ordinary room temperature, whilst the power of hydro- 

 lysing Maltose is not affected. W. Neilson Jones. 



Haynes, D., The gelatin isation of pectin in Solutions of 

 the alkalies and the alkaline earths. (Biochem. Journ. 

 VIII. p. 553—583. Oct. 1914.) 



The author gives a short account of the reactions and nature 

 of Pectin as at present known, Then foUows a detailed descriplion 

 of experiments that had for their object the study of the mechanism 

 of gelatinisation and its dependence on chemical change in the 

 case of pectin Solutions gelatinised bj'^ the action of the alkalies and 

 alkaline earths. 



It is shown that the rate of precipitation of pectin by the alka- 

 line earths is ver}'' nearlj^ proportional to the product of the con- 

 centrations of hydroxyl and metalic Ion, and that this product may, 

 with great probability, be taken as a measure of the rate of 

 gelatinersation. 



The foUowing theoretical implications are deduced: 



1. The rate of gelatinisation of pectin is not determined by the 

 rate of diffusion nor by the rate of surface adsorption of the alkali 

 or alkaline earths producing gelatinisation. 



2. It can be expressed as a velocity equation determined by the 

 concentration of the reacting substances, when the initial concen- 

 tration of pectin remains constant. 



3. It is therefore regarded as determined by the rate of a che- 

 mical reaction — the Substitution of a H by BaOH, K &c. 



That the reaction is of this kind is supported further by the 

 fact that the Constitution deduced for Compounds of the alkalies and 

 alkaline earths is strikingly analogous to that of the corresponding 

 Compounds of the mono- and disaccharides. Furthermore, gelati- 

 nised pectin forms solid Solutions with the alkaline earths that may 

 be compared with the solid Solution of lime and cane sugar. 



The pectin used in these experiments was prepared principally 

 from limes, though a little lemon pectin was also used. 



W. Neilson Jones. 



Jakouschkine, J., Ueber die Beziehungen zwischen dem 

 den Pflanzen leicht zu entziehenden Phosphorgehalt 

 und der Zulänglichkeit der Phosphornahrung. [Vorl. 

 Mitt.] (Journ. Opitnoi Agronomii. XVI. 2. p. 118—139. Petersburg. 

 1915.) 



Die vom Verf. angestellten Versuche ergaben folgendes: Bei 

 fettarmen Pflanzenteilen (Stengel) ändert der Auszug mit Alkohol 

 und Aether den Gehalt an Phosphorsäureanhydrid in den sauren 

 Auszügen nicht erheblich, Die direkte Fällung in Zitronensäure- 

 lösung führt zur genauen Trennung der mineralischen Phosphate 

 vom Phytin. Kombiniert man dieses Verfahren mit dem von Iwa- 

 noff, so erhält man noch genauere Resultate. Die Bodenfruchtbar- 

 keit wird am genauesten mittels des Gehaltes an mineralischen 

 Phosphaten im Stroh nachgewiesen. Ist dieser Gehalt geringer als 



