

1915] 



APPEL PHYTOPATHOLOGY AND SCIENTIFIC BOTANY 285 



cork in the cell walls near the places of infection occurs 

 earlier than the formation of cork plates. 



Of special interest is the physiology of inheritance. In this 

 lecture I wish merely to emphasize that the inheritance of the 

 unit characters and their behavior in the next generation is 

 one of the fundamentals of breeding resistant races. 



Finally, I must speak of anatomy. The necessity of the 

 examination of series of sections oblige the pathologist to 

 make use of the latest discoveries in histology. It is by way 

 of anatomy that we shall approach the problem of leaf-roll 

 of the potato. Onemjer has shown that the sieve tubes, which 

 have the function of providing the plant with albumen, are 

 destroyed in the leaf-rolling plants, similar symptoms occur- 

 ring in plants which suffer from other diseases only when the 

 plants are nearly dead. In leaf-rolling plants, however, we 

 find these changes from the very beginning, and we may use 

 them in diagnosis. Anatomy, likewise, points out relations be- 

 tween external disease symptoms and inner changes of struc- 

 ture. For instance, the three inner diseases of the potato, leaf- 

 roll, wilt, and bacterial ring disease, have distinguishable 

 anatomical characters ; the leaf-roll is a disease of the phloem ; 

 wilt, of the secondary wood vessels ; and bacterial ring, of the 

 spiral vessels. A thorough anatomical knowledge is of pri- 

 mary importance in all investigations concerning the inner 

 structure of healthy and diseased plants, the formation of 

 excretions and tyloses, and the different ways of recovery. 



I hope that it has been possible for me to show you that 

 phytopathology has many fundamental relations to scientific 

 botany, and that it further presents many important problems 

 for scientific investigation which deserve attention from the 

 botanical departments of universities. 



Should I have succeeded hereby in winning new friends to 

 phytopathology in this sense it would be a source of genuine 

 satisfaction and pleasure to me. 



