ATTITUDE OF PATHOIvOGISTS AND BACTERIOLOGISTS. II 



and Berthold, with the remark that recent experiments by van Tieghem on potato-tubers, 

 bean-seeds, cactus-stems, etc., seem to confirm these results. 



Otherwise expressed, these facts may be stated as follows : As a rule, saprophytic bacteria may, 

 under special conditions, attack, make sick, and destroy living plant tissues as facultative parasites. 



In the third edition of Zopf's Spaltpilze, published in 1885, bacterial diseases of plants 

 are discussed as follows: 



Much rarer [than in men and animals] are the cases in which we can speak of the genuine parasitic 

 action of schizomycetes in plant-organs. The best-known example is the familiar disease of potato- 

 tubers known as "wet -rot" caused by the butyric acid ferment (Clostridium huiyricum), through 

 which the tissues of the potato are entirely destroyed and converted into a vile smelling fluid-mass 

 (Reinke and Berthold). It remains to be seen whether the phenomenon known in Holland as "the 

 yellow disease of hyacinths," and recently described by Wakker, belongs here strictly speaking. Its 

 characteristics are the appearance of enormous numbers of yellow schizomycetous colonies in the 

 vessels and (at blossoming time) also in the intercellular spaces and cells of the parenchyma. 



Perhaps the rarity of schizomycetous diseases of plants lies in the generally acid reaction of 

 the juices of plants, perhaps also in their lower temperature as compared with the animal body, and 

 finally the formation of protective cork is perhaps also to be considered (p. 3). 



In the second edition of De Bary's Vorlesungen (1887) Arthur is said to have confirmed 

 and extended Burrill's work on pear-blight. 



In the second edition of his Handbook, published in 1886, Sorauer devotes 38 pages to 

 diseases due to bacteria, namely, to rot of the potato, white rot of hyacinth bulbs, rot of 

 onion bulbs, Comes's gummosis of the tomato, Prillieux's rose-red wheat grains, and various 

 stem and leaf reddenings. These pages deal with field appearances, the results of micro- 

 scopic examinations, and to a limited extent with what I have designated in vol. I as direct 

 infection experiments. Sorauer accepts the doctrine of bacterial disease of plants without 

 reserve and says: "Beyond doubt, in course of time, a large number of rot diseases will 

 be recognized." Of exact bacteriological methods there are no suggestions in this book. 

 Dr. Sorauer's own observations appear to have been limited to microscopic examinations 

 and a repetition of such crude infections as were made by Davaine, Hallier, Reinke and 

 Berthold, van Tieghem, and others. The bacteriosis which he had in mind is that which 

 occurs when tubers and bulbs are exposed to excessive moisture, with a restricted supply 

 of oxygen. From his own observations and experiments on potatoes, he could say with 

 reasonable assurance that "the wet-rot or rot may be produced artificially without the aid 

 of Phytophthora by inoculating bacteria into sound tubers. The decomposition phenomena 

 of the two diseases are essentially different." He had also observed that the bacteria could 

 penetrate through the open lenticels into the tubers. 



The statements in Sorauer's book on Die Schaden der Kinheimischen Kulturpflanzen 

 (1888) are essentially the same as in his Handbook, only much more condensed. His gen- 

 eral standpoint is expressed in the following sentence: "The bacteria are certainly much 

 more dangerous to living plants than has hitherto been recognized." 



De Toni and Trevisan in vol. VIII of Saccardo's Sylloge Fungorum (1889) gave 

 short descriptions of all the species of Schizomycetes known to literature. 



Under bacillus "Sectio 6 species endophytobiae, destruentes," the following species 

 are included: Bacillus vwillemini Trev., B. oleae (Arcang.) Trev., B. ampelopsorae Trev., 

 B. radicicola Beyerinck, B. hyacinthi (Wakk.) Trev., B. hyacinihi septicus Heinz, B. sorghi 

 Kell., B. amylovorus (Burr.) Trev. 



Laurent, writing in 1889, has the following: 



Many fungi which invade the higher plants have the property (propriete) of perforating the 

 cell membranes by the intervention without doubt of a special zymase. The germs of the ordinary 

 bacteria could easily penetrate into the leaves by way of the stomata when they are brought there 

 by the wind or other agents. But having reached the stomatic chamber, they would have to traverse 

 the cell membranes or to insinuate themselves between the cells. In order that this last mode of 



