67 



PLANT PATHOLOGY IN ITS RELATIONS TO OTHER 



SCIENCES. 



E. S. Reynolds. 



In pursuance of the thoug-ht that science is a unit and not 

 merely an aggregation of separate sciences, the relations of 

 various sciences to plant pathology are to be considered. This 

 science is defined as the study of the diseased conditions of 

 plants, and its importance, as indicated by the large losses to 

 the farmer caused by plant diseases, can not be overestimated. 



The relations existing between pathology and botany are 

 very close : In morphology we must study the natural and 

 diseased forms and structure of plants, as well as the morph- 

 ology of the attacking parasites ; in physiology the normal and 

 abnormal functions of host and of parasites must be investi- 

 gated ; from bacteriology many methods have been adapted to 

 pathological study, and, as many diseases are caused by bac- 

 teria, the paths of the pathologist and of the bacteriologist cross ; 

 many diseases attack our woody plants and greatly endanger 

 our forestries, thus bringing forestry and pathology into inti- 

 mate relations. 



When we turn to the other sciences, zoology attracts our at- 

 tention, for insects and other animals either cause or carry 

 many diseases. The diseased conditions in plants may cause 

 disease in those animals which feed upon them. Between chem- 

 istry and pathology some intimate relations exist. The manu- 

 facture and use of fungicides, and the contributions of chem- 

 istry to our knowledge of the normal and abnormal plant prod- 

 ucts make evident these relations. The problems in plant 

 pathology which relate to physics as well are even more subtle, 

 for in these we must study such questions as involve the process 

 of osmosis in plants, the a.scent of water in trees, etc., and the 

 influence of parasitic growth upon these processes. 



