No. 2, November, 1920] PHYSIOLOGY 119 



ties. Tannin is a strong protoplasmic poison since it strongly coagulates albumin. The 

 author found that tannin would easily coagulate egg albumin when alone, but when acetic 

 and tartaric acids were added, in small amounts in addition to tannin, coagulation did not 

 take place. Citric acid was not quite as effective. Albumin coagulated by means of tannin 

 would tend to return to its original sol condition after addition of acetic and tartaric acids. 

 Tannin appeals, and in fact accumulates, during I lie germination of some seeds in which it 

 was not originally present. It can not, therefore, be considered a- a reserve substance either 

 for the sugar or the other substances it may contain; the latter would indeed be injurious if 

 allowed to accumulate in the free state. The results of the investigation seem to justify the 

 following interpretation as to the significance and behaviour of the tannins in the plant: 

 The principal reason for the formation of these compounds is the property they have of being 

 more easily oxidized than the phenolic acids from which they are derived, tannins being much 

 more easily burned than gallic acid. This constitutes for the plant, deprived as it is of an ex- 

 cretory apparatus, a detail of the greatest importance, since it is a means of eliminating prod- 

 ucts that possess a high degree of toxicity. It is by this means that the tannins disappear 

 by complete oxidation in fleshy fruits wdien their coagulating power is no more neutralized 

 by the action of the organic acids which disappear during ripening. In other organs, instead, 

 an equilibrium is established between the former or accumulated tannins and those which 

 are destroyed by combustion. In peripheral organs such as the bark, directly exposed to 

 the action of atmospheric oxygen and to the influence of fluctuating external factors, the equi- 

 librium is subject to many fluctuations, especially is oxidation intensified with increase of 

 temperature, reaching a maximum during the warmest summer months. Tannins as gluco- 

 sides are then to be considered as refuse materials which the plant easily destroys, utilizing 

 the process of combustion, thereby initiated, for "vital" purposes. — A. Bonazzi. 



S3S. Gerhardt, Karl. Die Exkretion und ihre Bedeutung im Leben der Pfianze. [Ex- 

 cretion and its importance in plant life.] Naturwissenschaften 8: 7-8. 1920. — -The work of 

 Benecke, Amar, and especially Stahl, has shown that the oxalic acid formed in respiration 

 and possibly in assimilation, neutralizes the surplus (harmful) calcium in the plant. This 

 explanation of the role of oxalic acid has contributed much to a new understanding of the 

 exudation of water by the plant. This explanation of guttation, as developed mainly by 

 Stahl, is discussed at length. — Orton L. Clark. 



S39. Gola, G. Sulla presenza, nella piante, di composti ematoidi di ferro. [The presence 

 of haematin in plants.] Atti R. Accad. Lincei Roma Rend. (CI. Sci. Fis. Mat. e Nat.) 28 2 : 

 146-1.50. 1919. — From organic plant material, notably the leaves of Lemna and other water 

 plants, when extracted with boiling dilute HC1, a solution is obtained which shows positive 

 peroxidase properties. This solution was free from iron. If on the other hand you repeat 

 the extraction with ammonia, thereby getting the iron in solution, you obtain a residue which 

 reacts positively, although the iron has been extracted. This seems to indicate that in plants 

 Bach's theory, that the enzymatic peroxidase reaction is not dependent on iron, holds true; 

 and further, that the reaction is comparable to that obtained in animal chemistry, namely, 

 that the peroxidase property of the blood is not due to a combination of the iron with the 

 organic molecule. In this connection it is of interest to note that as regards distribution of 

 the enzyme in plants, most of it is found in the peripheral parts of the plant, in the tissues 

 of the phloem and the medullary rays, and that it is scarce in green tissues. — E. F . Artschu-ager. 



840. Greig-Smith, R. Contributions to our knowledge of soil-fertility. XVI. The search 

 for toxin-producers. Proc. Linnean Soc. New South Wales 43 : 142-190. 191S. — See Bot. Absts. 

 5, Entry 2281. 



841. Itano, Arao, James Neill, and Mary E. Garvey. Limiting and optimum reac- 

 tions for growth of B. botulinus and organisms isolated from food. [Abstract.] Absts. Bact. 

 4:3. 1920. 



