EARLY CONCEPTS OF DISEASE IN PLANTS 411 



ogy as the offspring. The purpose of this discussion is to bring 

 these interrelations into perspective. To anyone who attempts 

 to do this properly, it soon becomes apparent that the task is 

 herculean, for the reason that the subject matter of each field of 

 science is dispersed in a bewildering array of books, technical re- 

 ports, and bulletins. Manifestly it is impossible to accomplish 

 such a task within the scope of a single chapter. Moreover, to 

 date no one has attempted a comprehensive interpretative history 

 of mycologic and phvtopathologic development. Little more can 

 be attempted in this discussion than to point out a few of the land- 

 marks along the pathway, beginning with the completely un- 

 scientific era from which both mycology and plant pathology 

 emerged and ending with present-day concepts. Both fields, as 

 was briefly indicated in Chapter 1, Vol. I, had their beginnings 

 in the dim, distant past, long before the period of recorded his- 

 tory. The development of each has been dependent, as would 

 be expected, upon advances in such fields as bacteriology, medi- 

 cine, animal pathology, physics, and chemistry, and especially 

 upon the improvisation of new methods or techniques. 



EARLY CONCEPTS OF DISEASE IN PLANTS 



Some appreciation of the ideas concerning disease in plants that 

 prevailed before 1807 may be gained from a treatise by Re (1807). 

 Later Smith (1902, 1929), Arthur (1906), and Whetzel (1918) 

 sketched the background against which present-day ideas can be 

 interestingly evaluated. As these writers point out, man long 

 recognized the existence of disease, especially among cultivated 

 plants, but from earliest times such diseases were uniformly inter- 

 preted as supernatural phenomena and ascribed to offended deities. 

 Later came the belief, generally accepted among scientists, that 

 fungi were generated by the host or suscept on which they oc- 

 curred. The works of Unger, Meyen, and Hallier [Whetzel 

 ( 1918) ] are based on this concept. 



Certain other contemporary writers, however, held a different 

 opinion, as is shown by the observations of Fontana, published in 

 1767, in which he made the following statement regarding grain 

 rust: "We are dealing with a great number of hungry and in- 

 satiable plants that live by violence, feeding at the expense of the 

 tender green plant; they grow rapidly, thanks to the food that 



