314 Recognition in America 



plants. I am glad to be reassured on the subject, although I had no doubt 

 of the accuracy of your own work. 



[Alfred] Fischer's ipse dixit on the subject is calculated to exert an 

 unfortunate influence with those who have no special knowledge con- 

 cerning these investigations, as his book ^° is well written and on some 

 aspects of bacteriology it speaks authoritatively. 



I have recently had occasion to look up the evidence upon the influence 

 of proper disposal of sewage upon public health and I came across your 

 valuable monograph in the Annual Report of the Michigan State Board of 

 Health. I am ashamed to say that I did not know of it before. It is a 

 most admirable and convincing presentation of the evidence up to the day 

 of its publication. 



I shall be glad of the opportunity of studying the cultures which you 

 may send. 



Twelve days earlier, on November 10, Welch had opened 

 correspondence with Smith: 



Thank you for the reprint of your article on Pseudomonas Campestris, 

 which I am glad to have. I am much interested in it, as well as in what 

 you told me about bacterial diseases of plants on Monday last. I am sorry 

 that I was so busy with my class on that day, as not to be able to talk 

 more with you. 



I do not know what to make of A. Fischer's position in his Vorlesungen 

 iiber Bakterien (pp. 131 and 132) on bacterial diseases of plants. He goes 

 so far as to deny the possibility even of such diseases and expresses utter 

 skepticism as to all observations supposed to demonstrate them, being 

 indeed quite sarcastic on the subject [Welch here quoted a paragraph from 

 Fischer's book]. As Fischer is a botanist, and I suppose of good standing. 

 I do not understand his position. I had supposed that the demonstration 

 of bacteria pathogenic for plants was no less conclusive and generally 

 accepted than that for animals. 



Fischer, in his Vorlesungen iiber Bakteriau published in Germany 

 that year, not only denied that bacterial diseases exist in plants 

 but also argued their impossibility. The real causes of these dis- 

 eases, he believed, were of other origin. Bacteria could enter the 

 plant only through wounds. Stomatal infection was regarded 

 impossible. If the bacteria did get into the plant because of animal 

 injuries, frost, and other reasons, their development was stopped 

 by some formed cork substance. The contamination was sapro- 

 phytic; and genuine fungi accounted for many of the diseases of 

 plants now being attributed to bacteria.' 



91 



*" Vorlesungen iiber Bakterien, published in the last part of 1897 at Jena, Germany. 

 *^ See Bacteria in relation to plant diseases, op. cit., 2: 15-16. 



