No. 2, March, 1921] PHYSIOLOGY 203 



geotropic when grown in an atmosphere containing acetic acid. — From the experiments it is 

 concluded that the stem may be considered "of an 'alkaline' nature with electronegative par- 

 ticles in the disperse phase of the plasma membrane and that the root is of an 'acid' nature 

 with electropositive particles." — Theoretical explanations are also given of the orientation of 

 secondary and tertiary roots and stems. — I. F. Lewis. 



GERMINATION, RENEWAL OF ACTIVITY 



1367. KiDD, Franklin, and Cyril West. The role of the seed-coat in relation to the 

 germination of immature seed. Ann. Bot. 34: 439-445. 1920. — The germination of unripe 

 mustard seeds and peas from which the seed-coats had been removed was compared with 

 that of intact unripe seeds and with that of ripe seeds. It was found that the removal of 

 the testa accelerated germination, terminated the dormant period and increased the per- 

 centage of germination. It is concluded that the presence of the testa is largely responsible 

 for the dormant period when attempts are made to germinate unripe seeds, and evidence is 

 presented to show that the effect is due to the living testa limiting the gaseous exchange of the 

 embryo. — W. P. Thompson. 



1368. Hill, A. W. Studies in seed germination. Experiments with Cyclamen. Ann. 

 Bot. 34: 417-429. PI. 20, 15 fig. 1920. 



TEMPERATURE RELATIONS 



1369. KiESSELBACH, T. A., AND J. A. Ratcliff. Freezing injury of seed com. Nebraska 

 Agric. Exp. Sta. Res. Bull. 16. 96 -p., 22 fig. 1920.— See Bot. Absts. 7, Entry 623. 



1370. Manaresi, Angelo. Sui danni prodotti ai fiori degli alberi fruttiferi dalle gelate 

 primaverili in genere e da quelle in particolare dei giorni 28, 29 e 30 marzo 1918. [Damage to 

 flowers of fruit trees by spring frosts and in particular the frosts of the 28, 29 and 30 of March, 

 1918.1 Rev. Patol. Veg. 10: 1-26. 1919.— See Bot. Absts. 7, Entry 986. 



RADIANT ENERGY RELATIONS 



1371. Feuer, B., and F. W. Tanner. The action of ultraviolet light on the yeast-like 

 fungi. I. Jour. Indust. Eng. Chem. 12:740-741. 1920.— The data obtained indicate that 

 yeast cells are not very resistant to ultraviolet light. A majority of the organisms studied 

 were killed after an exposure to the rays of less than one minute. — Henry Schmitz. 



1372. Kogel, P. R. iJber Photodynamie. [Photodynamics.] Zentralbl. Gesamte Landw. 

 1 : 288-292. 1920. — Review of recent work, with bibliographical citations. — D. Reddick. 



1373. Laurens, H., and H. D. Hooker, Jr. The sensibility of Volvox to wave-lengths of 

 equal energy content. Jour. Exp. Zool. 30: 345-368. 1920. — The stimulation-time and the 

 rate of locomotion were ascertained in different regions of the spectrum all equal in energy. 

 The maximum effect in both was found to be near wave-length 494 mm- From this region the 

 effect decreased rapidly in both directions. These results agree closely with those obtained 

 by Mast on Chlamydomonas and blow-fly larvae; but they are at considerable variance with 

 those obtained on the more nearly related forms, Pandorina, Eudorina and Spondylomorum. 

 —S. 0. Mast. 



TOXIC AGENTS 



1374. Greig-Smith, R. The germicidal activity of the Eucalyptus oils. Part 2. The action 

 of the oils in aqueous dilutions. Proc. Linn. Soc. New South Wales 44: 311-347. 7 fig. 1919. 

 —See Bot. Absts. 7, Entry 1282. 



