AGBICULTTJEAL. BOTANY. 823 



The permeability of protoplasm to ions and the theory of antagonism, 

 W. J. Y. OsTERHOUT (Abs. in Science, n. sen, 35 (1912), No. 891, pp. 156^ 157). — 

 A description is given of experiments performed to test the electrical conduc- 

 tivity of living tissues in various solutions. 



The results show conclusively that a great variety of ions readily penetrate 

 living cells, and that antagonism between salts may be explained by the fact 

 that they hinder or prevent each other from entering the protoplasm. The ions 

 of sodium chlorid readily penetrate the protoplasm, but the addition of a small 

 quantity of calcium chlorid hinders this penetration. Such salts as the chlorids 

 of potassium, magnesium, caesium, rubidium lithium, and ammonium, and the 

 bromid, iodid, nitrate, sulphate, and acetate of sodium act in general like sodium 

 chlorid, while barium and strontium chlorids act like calcium chlorid. 



The mechanism of this action is not fully understood, but it is believed that 

 calcium, barium, and strontium chlorids bring about visible changes in the 

 plasma membrane which are quite different from those produced by such salts 

 as sodium chlorid. 



Investigations on the localization and function of potassium in plants, 

 T. Weevers (Rec. Trav. Bot. N^erland., 8 (1911), No. 3-4, pp. 289-332, figs. 3). — 

 A study is reported of a large number of plants representing the principal 

 groups and families of both the higher and lower plants to determine the 

 localization of potassium in their tissues. 



In all plants except the Cyanophycese potassium was found by the micro- 

 chemical method wherever employed. The nucleus was never found to contain 

 potassium, nor was it positively recognized in the cytoplasm. The greatest 

 amount of potassium in the cell is to be found in the vacuoles, none being 

 present in either the chromatophores or chlorophyll. Potassium salts can be 

 extracted from algal filaments and pollen tubes with a 50 per cent solution of 

 alcohol, and from dead spirogyra by water. The seeds and leaves of the horse 

 chestnut give up most of their potassium compounds in water cultures. Among 

 the phanerogams the potassium reaction is most pronounced in the paren- 

 chymatous tissues, especially in the growing points and resen'e organs. In 

 the vessels the reaction is weak, and in the path of the transpiration stream the 

 solution is very dilute. Potassium was found especially abundant in the living 

 wood, medullary rays, cambium, and in the unlignifled portion of the bark 

 parenchyma, while in the vessels and tracheids the reaction was very slight. 

 The medullary rays and other living portions of the plant seemed to serve as 

 storage organs for this substance. 



The localization of potassium leads to the hypothesis that it is specially con- 

 nected with the formation of protoplasm in the growing points. Its function 

 in the expanded leaf is unknown, but it is believed to be associated with the 

 synthesis and metabolism of proteids. In the vacuoles it is thought to regulate 

 turgidity. 



Observations on the physiological significance of cafEein, T. Weeveks 

 (Ann. Jard. Bot. Buitenzorg, 2. ser., 9 (1911), pt. 1, pp. 18-24). — A somewhat 

 polemical article, in which the author holds that caffein, like theobromin, is 

 formed as the result of secondarj' processes in the assimilation of albumin, that 

 it remains for a longer or shorter time as a storage product, and that it is 

 then used again in the synthesis of albumin. The presence of caffein in con- 

 siderable quantities in the seeds is explained by its assumed function as an 

 economical form of nitrogen storage. 



The influence of anesthetics on the osmotic properties of plasma mem- 

 branes, W. W. Lepeschkin (Ber. Deut. Bot. Gesell., 29 (1911), No. 6, pp. 

 349-355; abs. in Bot. CentU., Ill (1911), No. 24, pp. 626, 627).— This is an 



44616°~No. 9—12 3 



