280 PHYSIOLOGY [Bot. Absts., Vol. V, 



and in the roots passes upward in the spring through the xylem. He brings forward evidence, 

 derived from ringed stems, that this is not the case but that the food travels upward chiefly 

 in the phloem. — If a ring of tissues extending to the cambium is removed at the base of a grow- 

 ing twig, growth above the ring is reduced even if the leaves remain, and practically ceases 

 if the leaves are removed. This check to growth is probably due primarily to a lack of food 

 necessary for energy or for building material. If the leaves are left above the ring, enough 

 food is ordinarily manufactured by them to allow of considerable growth. The author sug- 

 gests that in some cases, especially where tissues above the ring tend to wilt, the check 

 caused by ringing may be due to an inability of the stem to carry up above the ring such 

 osmotically active substances as carbohydrates, and to a consequent inability to draw up 

 water osmotically. He finds that the osmotic concentration of the sap of a twig above a ring 

 is reduced, and is very markedly so if the twig is also defoliated. He suggests the importance 

 of the distribution of osmotically active substances as a factor in causing polarity. — Ringing 

 of the stem below a fruit was found to check the growth of the fruit. — Ringing of dormant 

 twigs was found to decrease greatly the growth of shoots coming from buds above the ring. 

 Such growth as took place was evidently at the expense of starch stored above the ring and 

 proportional to its amount, for at the cessation of growth this starch had quite disappeared. 

 In several species two rings, separated by from 15 to 107 cm., were cut out from dormant 

 twigs in early April, and the twigs examined for starch and sugar about a month later. In 

 all cases starch was found to be practically absent above the upper ring, very abundant 

 between the rings, and considerably less abundant below the lower ring and throughout a 

 similar twig which was unringed. Tests for sugar above, between, and below the rings gave 

 essentially similar results, sugar being much more abundant between the rings than else- 

 where.— From these facts the author concludes that although large amounts of carbohydrates 

 are stored in the xylem, there is no appreciable longitudinal transfer of sugars through this 

 tissue, but that to be translocated the stored food must pass radially into the phloem, where 

 it may readily be carried upward or downward. The author also suggests that at least some 

 of the mineral nutrients from the soil may move primarily through the phloem. — E. W. 

 Sinnott. 



2140. Kofler, Johanna. Der Dipmorhismus der Spaltoffnungen bei Pandanus. [Di- 

 morphism of the stoma ta in Pandanus.] Oesterreich. Bot. Zeitschr. 67: 186-196. S fig. 191S. 



2141. LeFevre, Edwin. Brine tolerance in certain rot organisms. [Abstract.] Absts. 

 Bact. 3 : 3^. 1919. — Softening of cucumbers in brine is caused by a wide range of bacteria, 

 among them being organisms causing soft rots, those destroying cellulose, and spore-bearing 

 aerobes. Bacillus vulgatus is probably the cause of much of the spoilage, since it has the high- 

 est sodium chlorid tolerance and fourth highest acid tolerance of 50 organisms tested. The 

 concentration of salt for preserving cucumbers is between 7 and 8 per cent. [From author's 

 abst. of paper read at scientific session, Soc. Amer. Bact.] — D. Roddick. 



2142. Loeb, Jacques. Influence of the concentration of electrolytes on the electrification 

 and the rate of diffusion of water through collodion membranes. Jour. Gen. Physiol. 2 : 173- 

 200. 16 fig. 1919. — Solutions of electrolytes when separated from pure water by a collodion 

 membrane affect the diffusion through the membrane in a way different from that of non- 

 electrolytes. The latter influence the initial rate of diffusion of water approximately in direct 

 proportion to their concentration, which the writer calls the gas effect, as it follows the laws 

 of gas pressure. This effect of the diffusion of water under the conditions of the experiments 

 was noticeable at concentrations above M/64 or M/32. Solutions of electrolytes may also 

 show this gas pressure effect upon the initial rate of water diffusion, but it commences only at 

 higher concentrations, usually at M/16 or higher. With weaker solutions of electrolytes, the 

 gas effect is not evident, but the rate and direction of diffusion of water is determined more 

 by the electrical charge of water, by the nature of the ions and the charges borne by them. 

 Two rules for the sign of the charge of the water were previously given (Bot. Abst., vol. 3, 

 Entry 1203). With an increase in concentrations of electrolytes up to about M/256 or above, 



