958 EXPERIMENT STATION RECORD. 



clear connection be detected between the quantity of sulphur dioxid in the leaves 

 and the distance of these from the centers of contamination. 



The author finds that the gas penetrates into the leaves solely through the stomata, 

 a fact that has been disputed by a number of writers. He distinguishes between acute 

 and chronic affection of plants, the former being due to the corrosive action of high 

 percentages of sulphur dioxid within a short period, and the latter to the slow action 

 of low percentages within a longer one. The author directs attention particularly to 

 the latter class of injury. Different plants were found to react in a very dissimilar 

 manner and to be unequally sensitive, and the author points out that it is necessary 

 to distinguish between sensitiveness of organs and the resistance of a plant as a 

 whole. 



It is claimed that sulphur dioxid was found to adversely affect photosynthesis, but 

 no critical concentrations could be established for different species. An inductive 

 action of the poison was frequently noticed, by which it was shown that there was a 

 direct action of the gas on the chloroplastids. In addition to corrosions due to acute 

 affection, the characteristic effects of a chronic nature were observed to be precocious 

 autumnal coloration and fall of the leaves and effects similar to these resulting from 

 partial starvation. The author discusses the mode of action of the poison on plants, 

 and believes that it unites particularly with the aldehydes present and that sulphuric 

 acid is liberated, the injury being due to this acid. 



The general features of chronically injured trees are said to be strikingly similar to 

 those due to defective nutrition, and the author attributes the effects to the indirect 

 action of sulphur dioxid on the soil, resulting in the removal of basic constituents 

 and the consequent acidification due to humic acids. As a remedy for chronic injury 

 the application of manures, especially basic ones, such as lime, is recommended. 



The probable bacterial origin of the gum of linseed mucilag'e, R. G. Smith 

 (Proc. Linn. Soc. X. S. Wales, 30 {1905), pi. l,pp. 161-174)-— -The production of gum 

 or slime in plants by bacteria is believed to be abnormal in the case of sugar cane, 

 various Leguminosse, etc., but in the case of linden, flax, and quince, gum and mucil- 

 age are of such common occurrence that it is not so easy to believe that the origin 

 may be bacterial. The author has examined the tissues of lime, quince, and flax 

 bacteriologically, and in all cases has found slime-forming bacteria. It is a matter of 

 common information that the seed of flax contains practically no starch, and that the 

 digestible carbohydrates consist chiefly in mucilage. 



In the present paper the auther gives an account of his studies with flax, and con- 

 cludes that the gums of flax mucilages vary in their chemical reactions and are prob- 

 ably of different chemical constitution. The product of hydrolysis consists of 

 galactose and reducing substances which yield indefinite osazones, and which are 

 possibly allied to the furfuroids of Cross, Bevan, and Smith. The gum bacteria in 

 the tissues of Linum are relatively very numerous and consist chiefly of races of 2 

 species. The chemical reactions of these gums are practically- identical with the 

 reactions of flax gum. The gum formed by one species is hydrolyzed to galactose, 

 and the other to galactose and a reducing substance that yields an indefinite osazone. 



The gum formed by bacteria is probably altered by the plant into mucilage and 

 other substances required in the plant economy. A number of the so-called species 

 of gum bacteria have probably one common origin, and the host plant can alter the 

 nature of the gum product which influences the growth characters. Two species, 

 Bacillus Uni land B. Uni II, are described as new. 



The ascent of water in trees, A. J. Ewart (Phil. Trans. Boy. Soc. London, Ser. 

 B, 198 (1905), pp. 41-85, figs. 5). — After briefly reviewing some of the theories 

 regarding the ascent of water in trees the author describes his investigations with a 

 number cf species of trees and shrubs, and shows the influence of various factors on 

 the conductivity of water. 



