24 EXPERIMENT STATION. [Jan. 



plants set in soil which contains decaying rootlets of diseased 

 plants usually become affected with the disease. In the case 

 of the tomato, a similar result does not follow. The report 

 gives an account of methods tried for the purpose of determin- 

 ing the cause of the mosaic disease in the tomato. The botanist 

 believes his experiments show that the disease is not caused 

 by an excess of any of the fertilizer elements. The mosaic 

 disease of tobacco may be so caused. The disease can be pro- 

 duced in tomatoes by severe priming, and is at least associated 

 with a deficiency of both the soluble and insoluble forms of 

 catalase in the foliage. 



The report of the botanist includes a suggestive paper on 

 the factors which underlie susceptibility and immunity to dis- 

 ease in plants. This paper emphasizes the necessity of as full 

 and perfect knowledge of the conditions essential for perfect 

 development as possible, and advances the view that when our 

 knowledge is sufficiently complete at this point it will be found 

 possible in large measure to avoid many diseases which at 

 present often prove highly destructive. We find the highest 

 development of cultural methods among American gardeners 

 and hothouse men. In the hothouse, where the climatic con- 

 ditions are largely under control, there is but little trouble 

 from disease when the conditions are fully understood and 

 the management skillful. In the case of out-of-door crops, 

 control of the climate being impossible, we may not be able so 

 fully to avoid disease ; but even with such crops, the most skill- 

 ful adaptation of soil, manure and culture to the requirements 

 of the crop will in large measure accomplish the same result. 



Entomological Department. — The report of this department 

 presents first a summarized statement showing the kind and 

 amount of the work of the year. Brief accounts are also pre- 

 sented of some of the leading lines of experimental work. One 

 of the most important of these is for the determination of the 

 resistance of different crops to fumigation with hydrocyanic 

 acid gas. These experiments are now complete for the cucum- 

 ber, and similar tests for muskmelons have been begun. 



Brief mention is made of experiments for the control of cab- 

 bage, turnip and onion maggots, concerning which, owing to 

 causes beyond control, no definite results can yet be presented. 



