THE MILLARDETIAN PERIOD 71 



Before passing to a brief consideration of the men whose 

 work and researches stand forth from among the multi- 

 tudinous contributions of this period, it may be pointed 

 out that the Millardetian period saw the beginning of 

 speciaHzation within the science. From the general field 

 were developed and split off in more or less independent 

 lines of development forest pathology and bacterio- 

 phytopathology. Within the general field a tendency 

 toward splitting up along crop group lines is also dis- 

 cernible, as, for example, diseases of fruit crops, diseases 

 of citrus crops, diseases of field and garden crops, etc. 

 This will be brought out more clearly in the discussion 

 of the pathologists and their writings. 



Modern pathologists may be divided, for the most part, 

 into two philosophic schools, the pathogenetists and the 

 predispositionists. The latter are the philosophic de- 

 scendants of the autogenetists, of which Franz Unger and 

 his period represent the highest development. The doc- 

 trine of this school collapsing before the revolutionary 

 discoveries of de Bary, Kiihn, and Pasteur, was main- 

 tained and somewhat readjusted to the new facts by 

 Hallier during the Kiihnian period. The pathogenetists 

 and their doctrine of pathogene responsibility in plant 

 disease production were distinctly the products of the 

 Kiihnian period. It will be recalled that, in reaUty, the 

 first of these, Fabricius the Dane, had lived and an- 

 nounced the doctrine more than seventy-five years 

 before the appearance of de Bary's classic work on the 

 pathogenic nature of the smut fungi. But phytopatho- 

 logic thought was at that time unprepared to under- 

 stand and accept so revolutionary a doctrine. It re- 

 mained for de Bary and Kiihn to revive and prove it 



