19201 AGRICULTURAL BOTANY. 225 



Sap from tops of all plants ■rrowii in sand and soil cultiiros or wator ouUures 

 of (lifforcnt concentrations and reactions has almost the same pH concentra- 

 tion, ai»proximately 0.0. Samples of sap from plants jirown on six diflerent 

 soils under the .same climatic conditions were found to have much f^reati-r con- 

 centration than that of the soil solution. 



Semipermeable membranes in plants, A. Rippel (ficr. Dent. Hot. GencU., S6 

 (1918), \o. .'/, pp. 202-,^ J 8). — This is lar{r<'l}- a review of findings and views of 

 other workers. The author holds tliat, while no completely .satisfactory evidence 

 has been obtained regardijig the existence of seuiii>ernieability in cliemically 

 pure cellulose membranes, yet this property does reside in cell membranes gen- 

 erally excei)t where they have uiulergone certain alterations which are indi- 

 cated. 



The influence of certain ductless gland substances on the growth of 

 plant tissues, R. A. Bldington (Biol. liul. Mar. Biol. Lab. Woods Hole, 31 

 {i:il9), Xo. 3, pp. J88-193, fig. i).— This paper reports the morphological effects 

 of thyroid constituents'" on the growth of the root tips of Allium, the experi- 

 ments being repeated three different years in midwinter and early spring, when 

 the dormant period of growing of the bulbs is naturally terminating. 



It appears that the growth of root tips of Allium is retarded by thyroid 

 gland material in a degree approximately proportional to the amount present. 

 The pre.sence of this material in the nutrient fluid does not, however, modify 

 the growth of the early leaves. lodin as potassium iodid has no appreciable 

 effect on growing root tips. Pituitary substances up to two grains of the dessi- 

 cated gland and supra-renal substances up to one grain of desiccated gland in 

 120 cc. of nutritive solution have no effect on tlie growing root tips of Allium. 

 It thus appears that thyroid constituents may influence protoplasmic action in 

 cells other than those of animal tissues. 



Ionization of air by plants, A. Ursprung and A. Gockel (Brr. Deut. Bot. 

 Gcurll., 36 (1918), Xo. J,, pp. 18.1,-192).— T\\e authors state that the ionization 

 observed by them is explainable on a purely physical basis, no support having 

 been given by their studies to a supposed ionization of the air through physio- 

 logical processes. 



Chemical constituents of Amaranthus retroflexus, M. L. Woo {Bot. Gaz., 

 €8 {1919), No. 5, pp. 313-344, figs. 11).— The author finds that the organs of A. 

 retroflexus contain a large amount of nitrate, the stem and branches being the 

 primary storage organs for this constituent. The rate of nitrate absorption 

 Increases with the age of t^ie plant. This high capacity for. nitrate absorption 

 and storage is thought to be an important factor in making Amaranthus a suc- 

 cessful competitor against cultivated plants. Carbohydrates and nitrogen com- 

 pounds show throughout the growing period fluctuations which are approxi- 

 mately in inverse ratio to each other. Analysis' of the seeds shows a high con- 

 tent of organic and a low content of inorganic phosphorus. The distribution of 

 nitrogen in .seeds is in the same order as that of the pho.sphorus. The predomi- 

 nating sugars in the seeds are the polysaccharids. These compose nearly one- 

 half of the total dry weight of the .seeds. 



Storied or tier-like structure of certain dicotyledonous woods, S. J. 

 Uf.(ord (liul. Torreg Dot. Club, 46 (1919), Xo. 1, pp. 2.53-273).— A study has been 

 made by the author of dicotyledonous woods characterized by a storied or tier- 

 like arrangement of their .secondary elements, representing a wide range of 

 natural orders and families. The .storied structure is found also in the second- 

 iry phloem. This structure appears on longitudinal sections, typically the tan- 

 ;ential, as tine transverse striations or ripple marks often visible to the naked 

 ?ye. They are constant enough in stems of considerable thickness to .serve as 

 1 valuable diagnostic feature. In some woods pit areas on the fibers are in 



II 



