BOTANY. 227 



tion, periodicity of stomata, etc. It was found that on clotidy and stormy days, 

 when the intensity of the light is uniform, the transpiration curve shows a pronounced 

 maximum near midday. Tlie illumination of an electric light of 900 candle- 

 power under uniform external conditions demonstrated a jjeriodicity in the trans- 

 piration of several plants that corresponded in the main with the curves determined 

 on cloudy days. Slight variation in the humidity of the atmosphere produced no 

 change in the amount of transpiration that could be definitely determined. An 

 increase of 8 per cent in the humidity resulted in a marked drop in the rate of trans- 

 piration. The curve of transpiration in the dark was frequently characterized by 

 marked variations in comparison with the periodicity of light. There is believed to 

 be a cessation of the vital action of the plant in the dark, and the retarding of the 

 rate, together with its more pronounced regularity, is in keeping with the loss of 

 vigor in the plant. The transpiration in the dark indicates that the stomata may be 

 sufficiently open to allow the escape of vapor. This may be brought about in con- 

 nection with the interchange of the gases in respiration or possibly V)y the independent 

 action of certain stomata that are especially affected by the increased turgor tension 

 or vapor tension of intracellular transi:)iration. The physiological character of 

 transpiration is indicated by the periodicity of the opening and closing of the sto- 

 mata. They are more resiionsive to the stimuhis of light in the morning than in the 

 afternoon, and the increased physiological activity in the morning is manifested in 

 the more pronounced after effect following the illumination in the forenoon. 



Contributions to the chemistry of chlorophyll, E. Schunck {Proc. Roy. Soc. 

 [London'], 69 {1902), No. 4^5, pp. 307-312; ahs. in Bot. Centbl, 89 {1902), No. U, pp. 

 389, 390). — A report is given of the changes which chlorophyll undergoes in passing 

 through the bodies of animals. The feces of animals fed green vegetable food did 

 not contain any chlorophyll, but did show a number of substances that are aiij^ar- 

 ently chlorophyll derivatives. One of these seems identical with phylloxanthin, 

 while another resembles phylloeyanin, but is not identical with it. A third sub- 

 stance was found to which the name scatocyanin is given. The chemical and 

 physical properties of scatocyanin are described. 



The etiolation of plants, F. Noll {Sitzher. Niederrhein. Gesell. Naiur. u. Heilk. 

 Bonn, 1901, jjp. 9; ahs. in Bot. Centbl, 89 (1902), No. 13, pp. 363, 364).— In addition 

 to the well-known action of the absence of light in producing the etiolation of plants, 

 the author describes forms which are due to other causes. The action of water under 

 special circumstances may result in etiolation, and an inadequate amount of nitrogen 

 or other important food constituent may result in a similar condition. Another 

 form of etiolation may be produced by propagating such plants as Sempervivium 

 and other rosette-forming plants by their flowering shoots. 



The action of light on etiolated plants, H. Kicome {Rev. Gen, Bot., 14 {1902), 

 Nos. 157, pp. 26-40; 158, xyp. 72-88; 159, pp. 120-137, ph. 3, figs. 10) .—The result of 

 a series of investigations on the influence of light upon etiolated plants is reported. 

 Potatoes, beans, lentils, castor beans, and a number of other plants were germinated 

 and part of the seedlings kept in the dark for several weeks and afterwards brought 

 into the light, a check lot being grown under normal conditions. The effect of etio- 

 lation upon the subsequent development of the plants is shown in the modified mor- 

 phological and anatomical structures of the plants. It is shown that etiolated plants 

 are capable of considerable development when brought into the light, provided they 

 possess sufficient reserve material when brought from darkness into light, and that 

 their capacity to grow has not been destroyed by the sudden change. The ultimate 

 development and differentiation of leaves produced in darkness when brought into 

 the light depends upon the state of development at the time of the change. The 

 same is true for the internodes, although these organs do not attain their maximum 

 development in the light. This effect seems to be brought about by a loss of water 

 due to the disturbance of the equilibrium between the transpiration by the leaves and 



