330 EXPERIMENT STATION EECOED. [Vol.38 



Uie containers, more particularly while the water is warm, calcium being 

 apparently the sole or chief constituent which is influential in this connection. 



The influence of calcium salts on absorbing' root hairs, H. Coupin (Conipt. 

 Rend. Acad. Set. [Paris], 16Jf (1917), No. 11, pp. G-'fl-GJf3).—Lepidium sativum 

 was exposed, after germination in tap water, to varying solutions of calcium 

 sulphate, carbonate, nitrate, or chlorid. It was found that the growth of the 

 root hairs was inhibited by the last three of these calcium compounds. 



The use of perphosphates in agriculture, N. A. Barhieri (Gaz. CMm. Ital., 

 47 [1917), I, No. 1, pp. 38-51).— It is stated that all the phosphorus contained in 

 animals or plants is in the form of soluble or insoluble phosphates. Plants do 

 not yield nor will they absorb monocalcium or dicalcium phosphate, these sub- 

 stances arresting germination of the seed or development of the plant. Cereals 

 or legumes from soils furnished with perphosphates contain less total phos- 

 phorus than do those from neighboring soils lacking perphosphates. Perphos- 

 phates may kill seeds with which they come into direct contact. 



Studies in greenhouse fumigation with hydrocyanic acid: Physiological 

 effects on the plant, W. Moore and J. J. Willaman (C7. S. Dept. Ag)-., Jour. Agr. 

 Research, 11 {1917), No. 7, pp. 319-838, pi. 1, figs. 11).— In continuation of in- 

 vestigations previously reported (E. S. R.,38, p. 158), the authors have conducted 

 a study to determine the action of hydrocyanic acid gas on the tissues of the 

 plant. All of the investigations have been conducted at the Minnesota Experi- 

 ment Station. 



It has been found that plants subjected to hydrocyanic acid fumigation absorb 

 more or less of the gas, the immediate effect of the poison being a reduction in 

 the activity of the oxidases and catalase and hence in respiratory activity. 

 Following this action, there is an inhibition of photosynthesis and translocation 

 of carbohydrate and a closing of the stomata. The permeability of the leaf' 

 septa is said to be increased and this causes less rapid intake of water from the 

 stems and more rapid cuticular transpiration. In mild cases this may result in 

 merely a temporary wilting, while in more severe fumigations the wilting is 

 followed by disintegration and death of the tissues. The authors claim that the 

 primary effect of the presence of hydrocyanic acid in a plant is a disturbance 

 of the oxidase and catalase activities, all other physiological effects being 

 secondary to this. 



The physical control of vegetation in rain-forest and desert mountains, 

 F. Sheeve (Plant World, 20 (1917), No. 5, pp. 135-1 Jfl).— The purpose of this 

 waper is to bring out some of the contrasts between the manner of control of 

 vegetation by conditions in the humid mountains of a tropical island and that in 

 the arid mountains of a temperate continental region. The basal details are to 

 be found in the author's publications previously noted (E. S. R., 32, p. 748; 36, 

 p. 27). 



Calling attention to instances illustrating the fact that two mountain ranges 

 may differ greatly in flora while having practically identical controlling envi- 

 ronmental factors, the author shows that the actual factors which underlie the 

 topographic control of the vegetation in the desert mountains of Arizona and 

 those in the Blue Mountains of Jamaica are diametrically opposed. 



Critical flowering and fruiting temperatures for Phytolacca decandra, F. E. 

 Lloyd (Plant World, 20 (1917), No. 4, pp. 121-126).— The author has made ob- 

 servations on pokeweed in two diverse climates widely different from that of 

 its native habitat for several years, during which time it produced seed only 

 under certain exceptionally favorable circumstances at Carmel, Cal. He con- 

 cludes that if the prevailing day temperatures, which are normally low enough 

 to prevent reproduction by the seed, were 5° warmer during the warmest hours 



