AUTHOR'S PREFACE. 



lx my research work, and in connection with my lectures at 

 the University and Technical School of Munich, I have for 



t/ 



some time felt convinced that there existed a very evident gap 

 in the literature relating to the diseases of plants. There was 

 need of a newer and more complete work on cryptogamic para- 

 sites and the diseases induced by them on higher plants, a work 

 furnished with many accurate illustrations, with a survey "t' 

 the newer literature, and with a general part wherein parasitism 

 and the relations between parasite and host arc discussed from 

 a botanical standpoint. Therefore, I have undertaken to write 

 a book intended to supply in some degree this pressing want. 

 1 1 ere the attempt has been made for the first time to review 

 in a general ami comparative manner the biological, physiolo-ical. 

 and anatomical relationships accompanying the phenomena of 

 parasitism. Already 1 >e I'.ary has considered the varying degrees 

 of parasitism and the phenomena of symbiosis in his celebrated 

 Mni-jilnilnii;/ n ml A'/cA///// of t/ti' Fiiii'j! ; while \Vakker lias laid 

 the foundations of our knowledge of the alterations in the 

 anatomy of plants diseased by the a-eiiey of fungi, more especially . 

 however, those alterations accompanying 'hypertrophy.' I venture 

 to continue this ditlicult and comprehensive chapter of plain 

 physiulogv, because- for ten years 1 have devoted my time to 



the study of plant pat holo-y. The 1 k may lie all the n 



aceepiable since I have continued a large number of the 

 observations and added the results of my own investigations. 

 many of them now published for ihe lirsl time. 



The prc-.-nt time is favourable to my \\ork. '1'lie great 

 S'////'/. /-'it/ii/n nun of Saccanlo (\\ith its appendices in Yols. i\. 

 and \.) has been recently completed: the classic invcs! i-at ions. 



