120 PHYSIOLOGY [Bot. Absts., Vol. VI, 



842. Masoni, G. Saggi sui succhi radicali. Prima nota. [Tests on root saps. First 

 contribution.] Staz. Sper. Agr. Ital. 52 : 569-583. 1919.— The present investigation was under- 

 taken by the author in connection with the question of chlorosis of plants due to excess of cal- 

 cium in the soil, and it covers only one phase of the question as it relates to the behaviour of 

 the root sap to various solutions rather than the root excretions. Experiments were made 

 with Cichorium, Zea, Lupinus and Daucus by crushing the roots and extracting them with 

 cold water and using the filtered solution. Solutions of ferric chloride 1-2 per cent were added 

 in the presence or absence of an alkaline solution of ammonia, or lime water. In other cases 

 ferric citrate, citric acid, nitric acid, acetic acid, dipotassium citrate, sodium acetate, glu- 

 cose, and saccharose were used together with the ferric solution. The results of the investi- 

 gation are thus summarized: Under equal conditions juices of various plants act differently 

 towards the ferric solutions, some causing a complete precipitation of the iron — although the 

 solution be acid — others leaving the iron in solution. The presence of ferric citrate, citric 

 acid, or dipotassium citrate avoids the precipitation of the iron. This action is not exerted 

 by equivalent amounts of acetic acid, sodium acetate, or nitric acid. Sugars have only a 

 negligible action in preventing the iron from becoming insoluble, and in concentrations of 

 as much as 40 per cent of saccharose the action was very slight. The juice of Daucus was 

 the most active in maintaining the iron in solution, while the juice of Lu-pinus and Zea follow 

 in the order given. In the latter plant the sap of the stalk at flowering time gave the same 

 reaction as the root sap. The author excludes the possibility that the insolubility may be 

 due to the action of tannic substances, and is more inclined to believe that the phenomenon 

 is due to the combined action of colloids, proteins, and possibly also to the phosphates to 

 be found in the juices. The method is, according to the author, applicable to the study of 

 the fate of ferric substances after their entrance into the plant rather than to their prepara- 

 tion for absorption by the plant. The principal consideration in these investigations is the 

 assumption of two sets of substances active in this connection: the one — probably made up 

 of proteins — capable of rendering the iron insoluble, and the other capable both of counter- 

 acting this first one and of dissolving the precipitate after it has been formed. Therefore the 

 circulation of mineral iron in the plant is dependent upon these two groups of substances, 

 and this condition may have an important bearing upon the adaptation of plants to various 

 media. — A. Bonazzi. 



843. Olitsky, Peter K., and I. J. Kligler. Toxins and antitoxins of B. dysenterlae 

 Shiga. [Abstract.] Absts. Bact. 4: 18. 1920. 



844. Teodoresco, Em. C. Sur la presence d'une phycoerythrine dans le Nostoc commune. 

 [On the presence of a phycoerythrin in Nostoc commune. 1 Rev. Gen. Bot. 32: 145-160. 2 pi. 

 4 fig. 1920. — Nostoc commune varies widely in color. The author found material giving red 

 pigment, but no blue pigment, in solution when macerated. Both pigments (phycoerythrin 

 and phycocyanin) are usually present in varying proportions. Solutions of many shades of 

 color ranging from red through blue to violet were also obtained from other material. From 

 all of them a red pigment was isolated by differential capillary absorption by filter paper. 

 The red aqueous solution obtained when red zones of filter paper were placed in water had a 

 yellow-orange fluorescence like that of phycoerythrin. Its spectrum showed the same 3 

 absorption bands with the same relative intensities as are seen in phycoerythrin from Cera- 

 mium rubrum and other red algae (Kylin and other authors) as well as in the red pigment from 

 Oscillatoria Cortiana (Bocat). Its reaction to acids, alkalies, and other reagents are essen- 

 tially the same as those of phycoerythrin from red algae. Solutions of the red pigment to 

 which antiseptics had been added, and which were kept in the dark, remained unchanged for 

 2 years. When such precautions were not taken decomposition occurred. During the first 

 stages of this decomposition the relative intensity of the 3 absorption bands is reversed, pre- 

 cisely as in the case of phycoerythrin from Ceramium and also the red pigment from Oscilla- 

 toria (Gaidukow). — The author concludes that the red pigment in Nostoc commune and other 

 Cyanophyceae is the same as that in the Florideae, and not merely a variety of phycocyanin 

 to which it is closely related, but from which it differs decidedly in its spectrum. Phycoery- 



