536 



SCIENCE 



[N. S. Vol. XLII. No. 1085 



lamps, illuminating gas with welsbach mantle, 

 acetylene and finally the flat-wick kerosene 

 flame. None of these other sources gave ex- 

 actly the same color values as daylight. How- 

 ever, the approsimation to daylight was sur- 

 prisingly good, and the worst one, i. e., the 

 kerosene flame, gave better color values than 

 the best artificial light without the color 

 screen. The original intensity of the carbon- 

 filament lamp and the kerosene flame is not 

 great enough to give the best results with the 

 daylight glass. This is because much of the 

 artificial light must be absorbed to render it 

 like daylight. 



To the writer it seems that this glass must 

 be a great boon to all those who must use the 

 microscope with artificial light. As the light 

 is soft like that from a white cloud, the com- 

 fort to the eye is most gratifying; and of al- 

 most equal importance, it gives certainty in 

 distinguishing the most delicate colors and the 

 various combinations of colors. It seems, fur- 

 thermore, to promise great help in the textile 

 and dye industries, in chemistry and in medi- 

 cine, as it offers a standard daylight without 

 the changes of real daylight depending on 

 whether the sun is shining or whether the 

 light is from the blue sky or from a cloudy 

 sky. And finally it is believed from the ex- 

 periences of the writer, that it will furnish 

 great relief to those with sensitive eyes who 

 must work by lamp-light, as it renders the 

 light soft and agreeable like the most favorable 

 daylight. 



Simon H. Gage 



Laboratory of Histology and Embryology, 

 Cornell University 



A NEW alfalfa LEAF-SPOT IN AMERICA 



While passing an alfalfa field in the vicin- 

 ity of Manhattan, Kans., in October, 1914, the 

 writer's attention was attracted by the irreg- 

 ular stand, which was noticeable from the 

 road. Since light frosts were rather frequent 

 at the time of year, the condition of the 

 alfalfa was at first thought to be due to these, 

 but closer examination indicated that these 

 could not be the cause. Careful investigation 

 showed that a leaf -spot was prevalent on many 



of the plants, and that it was strikingly dif- 

 ferent from anything with which the writer 

 was familiar. 



The plants affected were not producing a 

 normal amount of foliage, the stems being 

 sparsely set with spotted leaves, which were 

 affected with a singular leaf-spot. The dis- 

 eased plants thus presented an unthrifty ap- 

 pearance, and were also somewhat smaller than 

 normal plants. 



Since this was discovered on the last crop 

 of the season, there was a question in the 

 writer's mind whether it would be confined 

 mainly to the latter part of the aHaHa season, 

 or would make its appearance on the earlier 

 crops. In the present season a close watch was 

 kept on the first crop. The disease was again 

 located in the aforementioned field on April 

 11, 1915, and further investigations have shown 

 it in a number of fields belonging to the agri- 

 cultural college. Furthermore, specimens have 

 been collected in different localities within 

 this state and other states. It has likewise ap- 

 peared to a greater or less extent in the second 

 and third crops in Kansas. 



The material collected last fall was studied 

 in the laboratory this winter, and cultural and 

 inoculation experiments are now under way. 

 There is no question as to its pathogenicity. 

 The fungus is an ascomycete, the perfect stage 

 (perithecia) being found in the mature spots. 

 It belongs to the genus Pleosphosrulina. The 

 writer has been unable to locate any literature 

 pertaining to its occurrence in America. The 

 species has not been definitely determined. 

 An alfalfa leaf-spot due to Pleosphcerulina 

 Briosiana Pollacei has been reported by Pol- 

 laeci,^ Bubak^ and Puttmans,^ in Italy, Aus- 

 tria and Brazil, respectively. There is some 

 doubt, however, whether the species with which 

 the writer is working is Briosiana Pollacei, 



i"Spora una nuova malatta deil erba medica," 

 Atti del Instituto Botanico, deW Universita di 

 Favia, Nuova Serie, Vol. II., Serie 1901. 



2 ' ' Eine neue Krankheit der Luzerne in Oster- 

 reicli, ' ' Wiener Landwirtsehaftliche Zeitung, Nov. 

 20, 1909, Nr. 93, s. 909. 



3 ' ' Diseases of Cultivated Plants, ' ' Eevista 

 Agricola Sao Paulo, Nos. 114-125, pp. 379-381, 

 1905. 



