AGRICULTURAL BOTANY. 731 



solutions are unable to penetrate it. Protoplasm considered in its entirety as 

 a membrane is then a modifiable membrane. 



The author claims to have establLshed 2 facts as to the toxicity of the salts : 



(1) The toxic action of a molecule is approximately a property of acid and 

 basic radicals for a large number of salts, while this is due to properties ac- 

 quired by the molecule by reason of its nonsaturation by the acids and bases ; 



(2) the toxic siilts are those which do not penetrate at all or only with diffi- 

 culty the living protoplasm when they are employed in weak solutions, while 

 solutions of nontoxic salts, on the contrary, easily penetrate the protoplasm. 

 As to the nature of protoplasm it seems to be a very unstable substance as 

 regards a large number of salts. 



On the mineral nutrition of vascular plants based on the root structures, 

 J. DE RuFz DE Lavison (Rev. O^n. Bot., 23 (1911), No. 269, pp. 177-211, figs. 

 2). — In a further investigation on this subject (see above) the author holds in 

 addition to the facts itreviously noted that the endodermis of roots acts as a 

 sort of filtration medium for the salts able to penetrate the protoplasm, the 

 intensity of this filtration power depending upon the nature of the plants, the 

 kind of salt, and the age of the protojilasm of the endodermis. 



The role of manganese in plant nutrition, P. Leidbeiteb (Studien uber das 

 Yerhaltcn des Mangaii.s im Bodcn ::u einigenlanduirtscliaftHcheti Kulturpflnnzen 

 (Hafer), Pferdcbohne, i^cnf, Kartoffeln, Zucker- and Runkelriihen. Inaug. Diss., 

 Rostock, 1910, pp. 70; ah.s. in Eriuihr. Pfianze, 7 {1911), No. 6, p. 53, fig. 1; Rev. 

 Set. [Paris], J,9 {1911). I, No. 17, p. 536; ZentU. Agr. Chem., J,0 {1911), No. 8, 

 pp. 531-535). — Compounds of manganese have increased the yield of oats, mus- 

 tard, beets, and potatoes. The green color was especially accentuated in the case 

 of oats and beans, and the action of manganese manifested itself about the fifth 

 week of growth. Beans wei-e found to assimilate the largest doses of man- 

 ganese, though an excess was easily shown to be injurious to them. Twenty- 

 five mg. of manganese per liter of the nutritive solution was injurious to oats, 

 and a solution of 0.5 gni. of manganese i)er liter killed oats after 2 mouths. 

 Oats tolerated a greater proportion of manganese when grown in the soil than 

 when grown in nutritive solutions. The addition of manganese to so^ls increased 

 the sugar content of beets and the starch content of potatoes. 



The action of manganese showed itself best on humus soils, to a less extent 

 on clay soils, and least on sandy soils. It was found that the phosphate or 

 nitrate of manganese was able to become a source of phosphoric acid or of 

 nitrogen, the nitrate being absorbed most readily. Young plants were much 

 richer in manganese than mature ones, while the leaves were the richest and 

 the stems the poorest in manganese compounds. 



A theory regarding the manganese soils and pineapples, C. C. James 

 {Hawaii. Forester and Agr., 8 {1911), No. 6, pp. 176-178). — In a brief discus- 

 sion of the manganese soils of Hawaii, the mineral content of pineapples and 

 sugar cane, and the various manganic compounds, the author assumes that the 

 toxic action of these manganese soils on pineapples is due to the action of 

 calcium mangauite primarily and to the secondary action of other salts and 

 acids upon the calcium manganite. 



The phosphorus assimilation of Aspergillus niger, A. W. Dox (.46s. vn 

 Science, n. ser., 3-i {1911), No. 868. p. 218). — The author reports that a number 

 of phosphorus compounds were readily utilized by this organism in culture 

 media. 



On the histological relations between Cuscuta and its host, Maey G. 

 Thoday (Sykes) {Ann. Bot. [London], 25 {1911), No. 99, p-p. 655-682, pis. 3).— 

 This is a study of the origin of the protoplasmic connecting threads in plant 

 tissues, in which by a careful histological investigation of the haustoria of 



