472 Physiologie. 



The authors find the beans to contain a cyanogenetic 

 glucoside which they term phaseolun at in. Its composition 

 is CioHi-OgN. When hydrolysed by emulsin or dilute acids 

 it yeilds acetone, dextrose, and hydrocyanic acid. 



Warmed with dilute alkali, phaseolunatinic acid and am- 

 monia are produced; by subsequent hydrolysis with dilute acids 

 the phaseolunatinic acid is split of into dextrose and a-hydroxy- 

 isobutyric acid. Therefore phaseolunatin is seen to be the 

 dextrose ether of acetone cyanhydrin, and its Constitution is 

 (CH 3 )2C(CN)-0-C 6 Hn05. 



1t thus constitutes the first member of a new class of natu- 

 ral cyanogenetic glucosides, containing as it does the aliphotic 

 nucleus; amygdalin, dhurrin, and lotusin, the other known 

 cyanogenetic glucosides being aromatic Compounds. 



The enzyme of the seeds is exactly similar in its effects 

 to emulsin. The so called „Rangoon" and „Paigya" beans used 

 as food for cattle also contain a little phaseolunatin. 



Under füll cultivation light coloured or white beans are 

 produced incapable of forming hydrocyanic acid; they contain 

 no phaseolunatin, though emulsin is present. This is quite 

 comparable with the case of the almond — the bitter almond 

 containing amygalin and emulsin, while the sweet almond 

 contains emulsin only. 



Treub has suggested that in Pangium edule the at present 

 unknown precurser of hydrocyanic acid may play the part of 

 a formative material in the synthesis of amides and proteid. 



This is also probably true of the cyanogenetic glucosides 

 of Lotus arabicus, Sorghum vulgare and Phaseollis lunatus. 



The absence of the glucoside in cultivated forms of P. lu- 

 natus and the sweet almond may be the result of more active 

 metabolism induced by improved nutrition so that no glucoside 

 is available for storage in the seed. e. Drabble (London). 



Elfving, Fr., Die photometrischen Bewegungen der 

 Pflanzen. Einige Bemerkungen. (Ofvartryck af 

 Finska Vet.-Soc. Förhandlingar. Bd. XLIII. 1901. 5 pp.) 



Bei den phototropischen resp. taktischen Bewegungen der 

 Pflanzen ist nach Olt mann nicht die Richtung des Lichtes 

 das Maassgebende, sondern die Lage des Optimums resp. die 

 Richtung, in welcher sich die Intensität auf das Optimum hin 

 abstuft. Hinter einem keilförmigen Glaskasten, der mit einer 

 durch Tusche schwach getrübten Gelatinelösung gefüllt ist, findet 

 die Bewegung von Volvox- Kugeln, wenn sie sich an einer 

 Stelle mit bestimmter Lichtintensität ansammeln, senkrecht zur 

 Richtung der Lichtstrahlen statt. Diese Auffassung basirt sich 

 darauf, dass jeder Punkt Lichtstrahlen nur von einer Richtung 

 her empfängt, was doch nach Elfving nicht richtig ist; der 

 Punkt bekommt nämlich auch seitliches Licht. Hinter einem 

 Tusche-Gelatine-Prisma mit planparallelen Wänden ist doch die 



