264 BACTERIAL DISEASES OF PLANTS 



Reinke and Berthold, Kramer, Frank, Wehmer, and, prior to 

 Appel, all the Germans who studied potato rots (mostly by 

 means of the microscope) were led astray by the non-infectious 

 saprophytes (starch-destroyers, gas-producers, endospore-bear- 

 ing rods, coccus forms, etc.) which soon swarm in the tissues 

 and complete their destruction, but cannot be induced to begin 

 the rot except under very abnormal asphyxiating conditions. 

 Then, of course, almost any refuse-loving organism will grow 

 in the dead tissues, since the potato is a good culture medium 

 for man}^ things. In this connection, read Wehmer's paper in 



Fig. 201. — Streak culture of Bacillus phytophthorus Appel on raw potato 

 36 hours at about 23°C., showing a soft rot bordered by a dark stain. Inoculated 

 from a 48-hour culture on steamed potato. Tuber soaked 30 minutes in 1:1000 

 mercuric chlorid water before cutting with a sterile knife. The check }i remained 

 sound. Laboratory experiment of 1914. }4 nat. size. 



Centralblatt J. Bakteriologie, 2te Abt., IV Bd., 1898, pp. 540' 

 570, 627, 694, 734, 764 and point out his fallacies. 



Appel by his masterly paper (1903) let a flood of light 

 into an obscure situation, because while the writer had proved 

 conclusively 7 years earlier (1896) that a part of the potato rot 

 of the United States was due to a schizomycete, this organism 

 (Bacteriu7n solanacearum) had not been subsequently isolated 



