382 W. Wendler: Chemische Physiologie 1917— 1919 [126 



stoff im Reagenzrohr, schüttelt gut durch und läßt sie bei Zimmertemperatur 

 eine Stunde stehen. Nach Filtration ist die Lösung wochenlang haltbar. Verf. 

 teilt dann seine Untersuchungsergebnisse an verschiedenen Objekten mit. 



814. Debourdeaux, Leon. Die Bestimmung des Theobromins. 

 (Journ. Pharm, ('bim. [7], 15, 1917, p. 306.) — Ref. in Ctrbl. Biochem. Bio- 

 physik 19, 1918, p. 385—386. 



815. Degli, Atti M. L'aciditä d e i succhi i n a 1 e u n i v i t i g n i 

 e la loro resistanzä alle malattie. (Annali della R. Scuola Sup. 

 di Agricoltura in Portici 14, 1916 — 1917, 24 pp.) — Es besteht eine nahe Be- 

 ziehung zwischen der Widerstandsfähigkeit der Reben und der Azidität ihrer 

 Säfte. Die am besten widerstehenden Reben haben die sauersten Säfte. 



A. Borntraeger. 



816. Delauney, P. Extraction desglucosides de d e u x O r - 

 chidees indigenes; identification de ces glucosides avec 

 la Loroglossine. (Compt. Rend. Acad. Sei. Paris CLXXI, 1920, p. 435 

 bis 437.) 



817. Dixon, Henry H. and Atkins, W. R. G. Osmotic p r e s s u r e s 

 in p 1 a n t s. VI. — n the composition o f t h e s a p in the con- 

 dueting tracts of trees a t different levels and at d i f - 

 f erent seasons of the year. (Sei. Proc. Roy. Dublin Soc, 

 N. S. 15, 1916, p. 51 — 62.) — Summary: „1. Large quantities of 

 sap may, as a rule, be centrifuged from the condueting wood of trees. 

 This sap varies in colour and in electrolyte and non-electrolyte content. 

 2. When in a condition of physiological rest during late autumn and winter, the 

 osmotic pressure of the wood-sap of deeiduous trees is small and approximately 

 constant throughout; the stems, the roots, and upper portions of the stem 

 have, however, slightly pressure than the intervening portions. 3. During the 

 early spring the sap is enriehed by the addition of large quantities of sugars 

 from the storage cells of the wood-parenehyma and of the medullary rays 

 Accordingly the osmotic pressure rises in a very marked degree from root 

 to summit, the increase being particularly great in the upper regions. 4. During 

 the late spring the concentration of sugars is still considerable being roughly 

 half of the earlier value. The electrolytes of the sap are, however, present in 

 much greater concentration than in the early spring. 5. In Acer macrophyllum 

 reducing sugars are never foünd in the wood-sap, except in traces, whereas 

 sucrose is present in quantity. In the other trees examined both reducing sugars 

 and sucrose are present, the latter predominating as a rule. During the vernal 

 mobilization of reserves the reducing sugars consist of the hexoses and maitose; 

 at other times the latter is abseilt. 6. In evergreens and sub-evergreens the 

 seasonal changes are not very striking nor are the gradients of osmotic pres- 

 sures from root to summit as regulär as in deeiduous trees. The esmotic 

 pressure of the transpiration sap in the root exceeds that in the stem at certain 

 seasons." 



818. Dodge, Carroll W. T y r o s i n i u the f u n g i : Chemistry 

 and methods of study in g the tyrosinase reaction. (Ann. 

 Missouri Bot. Gard. 6, 1919, p. 71 — 92.) — Conclusions: „From the above data 

 we may conclude: 1) that the tyrosinase reaction is not a deamination, 

 although it is possible that deaminases may exist in the same organism with 

 tyrosinase; 2) that the tyrosin molecule, in which part of the carboxyl groups 



