224 EXPERIMENT STATION RECORD. [Vol.38 



On the mechanism of translocation in plant tissues. — An hypothesis with 

 special reference to sugar conduction in sieve tubes, S. Mangham {Ann. Bot. 

 ILomlon], 31 {IVll), No. 122, pp. 203-311, /i<js. 2).— This is a discussion oC the 

 data and views of various contributors regardiug the processes which occur in a 

 plant cell durliif; certain phases of su^^ar translocation with a view to developing 

 an outline of a working; hypothesis. 



It is stated that definite relations obtain between the solute concentration at 

 the surface of absitrhlni; particles introduced into the solution and the concen- 

 tration of the solute in the solvent, this state of equilibrium being reversible in 

 cases cited. 



The influence of light and chlorophyll formation on the minimum toxic 

 concentration of magnesium nitrate for the squash, Iv. B. Hakvev and K. H. 

 True (Amer. Jonr. Bot., 4 (1917), No. 7, pp. 407-410, figs. 2).— The minimal 

 toxic concentration of magnesium nitrate for squash grown in water cultures 

 was raised from 125 N X 10—" in darkness to 200 N X 10-° in light. This 

 change was presumably correlated with the removal of magnesium from toxic 

 compounds to form chlorophyll. 



The toxicity of galactose and mannose for green plants and the an- 

 tagonistic action of other sugars toward these, L. Knudson {Amcr. Jour. 

 Bot., 4 {1017), No. 7, pp. 430-437, figs. 4).— Having extended the studies pre- 

 viously reported (E. S. R., 35, p. 28; 36. p. 125) to include numerous experi- 

 ments with various sugars other than galactose, employing methods which are 

 described, the author shows that mannose also is toxic to the roots of some 

 plants, and that this toxicity is lessened by either glucose or saccharose. 

 Mutual antagonism was not found to exist between galactose and mannose. 



Dr. Beal's seed vitality experiments, H. T. Darlington {Rjit. Mich. Acad. 

 Sci., 17 {1915), pp. 164-166). — Giving some account of the progress of the series 

 of experiments conducted by Beal since 1879 (E. S. R., 17, p. 463; 24, p. 195; 

 34, p. 732), the author reports the results of liis endeavors to obtain germination 

 from seed samples taken out the thirty-fifth year. 



Of the 22 species originally employed, 8 are said to have failed to germinate 

 up to and after the fifth year, the remaining species germinating some years, 

 and Lepidium virginicum (probably also Rumex crispus) germinating every 

 year. The best results were formerly obtained by moistening the sand so as to 

 get a few seeds to come up, then allowing the sand to dry out partly, moistening 

 again, and so on, repeating this at varying intervals for several months. This 

 plan has been adopted by the author and the tests are reported as still in 

 progress. 



The nongermination of seeds of fleshy fruits, J. M assart {Bui. Sci. France 

 et Bclg., 50 {1016), No. S, pp. 167-160; abs. in Rev. Sci. [Paris], 55 {1917), No. 

 10, p. 309). — Tests of seeds of a number of dry or fleshy fruits in vegetable 

 juices, saccharose of different concentrations, and water are said to indicate 

 that the delaying influence of these juices on the germination of fleshy fruits 

 and their destructive action on dry fruits show a variation parallel to that of 

 their osmotic pressure, from which it appears that concentration is the condition 

 essential to such influences. Seeds of different plants are unequally sensitive 

 to these juices. The juice of the blackberry and that of watermelon appear 

 to be particularly injurious. 



Some factors concerned in the germination of rust spores, E. B. Mains 

 {Rpt. Mich. Acad. Sci., 17 {1015), pp. 136-140).— This work, initiated because of 

 the difliculty of obtaining germination during the summer months and done 

 mainly during the summer of 1914, was carried out principally with uredospores, 

 though a few teleutospores and secidiospores were tested. Details are given of 

 tlie tests and the results thereof in case of PuccvrUa coronata (P. coronifera or 



