130 EXPEEIMENT STATION EECOED. 



fertilizer ; with ordinary commercial fertilizer contaiuiug 4 per cent of nitrogen, 

 8 per cent of phosphoric acid, and 7 per cent of potash (with and without addi- 

 tion of manure) ; and with so-called mineral fertilizer, which is stated to be 

 ground rock containing no nitrogen and only traces of phosphoric acid and 

 potash. The yields were smaller with the rock fertilizer than on the unfertilized 

 plat. 



AGRICULTURAL BOTANY. 



The effects of artificial shading on plant growth in Louisiana, H. L. 

 Shantz (C7. S. Dept. Agr., Bur. Plant Indus. Bui. 219, pp. 31, pis. 6, figs. 11).— 

 The author gives a description of experiments conducted at Baton Rouge, La., 

 during April and May, 1908, in which an attempt was made to determine the 

 effect of different degrees of shade giving a definite series of light intensities on 

 plant growth, and also to ascertain to what extent the so-called shade effects 

 were independent of the resulting changes in other physical factors such as tem- 

 perature and humidity. 



Radishes, lettuce, potatoes, cotton, corn, and mustard plants were grown under 

 six different degrees of light intensity, and it was found that where the illumina- 

 tion was so decreased as to range from u/2 to n/7 a general increase in growth 

 resulted in potato, cotton, lettuce, and radish, as indicated by increased green 

 weight, height, and numbeir of nodes. Corn made its best growth in full light. 

 Where the light was i-educed to n/15 or less none of the plants were found able 

 to elaborate food material sufficient to produce growth after the seedling stage 

 was passed. 



In estimating the solar energy received during any considerable period of the 

 experiment, it was determined to be approximately 150 calories per square meter 

 per second, according to Abbot's measurements. Growth was best when the 

 energy received varied from 21 to 75 calories per square meter per second, while 

 photosynthesis practically ceased when the energy was reduced to 10 calories 

 per square meter per second or less. The apparent tolerance of shade exhibited 

 by the younger plants is believed to be due to the food supply still remaining 

 in the seed and not to any special ability of seedlings to cari-y on photosynthesis 

 in weak light. 



The effects of variations In temperature and humidity incident to shade were 

 so slight that they could not be detected by a comparison of the plants in the 

 bed in which these conditions were equalized by the use of an electric fan with 

 the plants grown in beds where no such conditions existed. Shade produced 

 such marked effects on plant growth that the effects of changes in humidity 

 and temperature were considered practically negligible. 



The effects of ultraviolet rays on vegetation, J. Stoklasa et al. {Biol. 

 Listy [Bohemia], 1912, p. SI; ahs. in Bot. Centbl, 122 {1913), No. 4, p. 90).— 

 The authors describe further experiments (E. S. R., 28, p. 529) with the mer- 

 cury vapor lamp, investigating, the influence of the dark rays on etiolated [ilant- 

 lets of Acer platanoides, Betula alba, Prunus cerasus, Syringa vulgaris, JEsculus 

 hippocastanum. Primula obconica, Begonia semperflorens, Aloe vera, Trades- 

 cantia virgimca, etc. 



In from one to two hours with the employment of a protective globe the 

 plants began to show a deepening green color. The rays did not alter the 

 chlorophyll of gi'een plants, but the leaves became a deep green and finally the 

 protoplasm was killed. Experiments with Azotohacter chroococcmn are said to 

 have shown that only the shorter ultraviolet rays kill the protoplasm. These 

 investigations are considered to show also the probable course of assimilation. 



A preliminary note on the coagulation of proteins by ultraviolet light, 

 W. T. BoviE {Science, n. ser., 37 (1913), No. 940, pp. 24, 25). — In order to gain 



