the; earIvIEst workers. 9 



MacDougal a collection of essays entitled Living Plants and their Properties. His cross- 

 inoculations of Uredineae in recent years have settled many doubtful points. For many 

 years he was one of the editors of the Botanical Gazette. 



Earlier than any of these writings is the paper by Woronin (1866) announcing the 

 discovery of bacteria in the root-tubercles of lupins. His conclusions were based simply on 

 microscopic examinations, but they were confirmed by Beyerinck two decades later (1888) 

 and since that date a great literature has arisen. Woronin studied under De Bary and 

 afterwards published several papers in conjunction with him. He was born in St. Peters- 

 burg and lived there during the latter part of his life. He is justly famous for his beau- 

 tifully executed monographs on various pathogenic fungi: Tuburcinia, Sclerotinia, etc. 

 Beyond this one early research, so far as known to the writer, he did nothing with bacteria. 



About the same time (1868) the Frenchman, Davaine, a man of marked originality 

 and excellent powers of observation, showed that certain bacteria were able to produce a 

 soft-rot in plants when inoculated, and this observation was subsequently confirmed by 

 van Tieghem and many others (see Destruction of Cell-walls, etc.). 



In conclusion, one ought not to forget Anton De Bary (1831 to 1888). The present 

 has its roots in the past and his profound influence still lives. De Bary published nothing 

 on bacterial diseases of plants but he made it possible for others to do so. Directly or 

 indirectly all the early workers in this field were influenced by him. The same is true of 

 those who followed, and all of us are much indebted to him. 



THE GENERAL ATTITUDE OF PATHOLOGISTS AND BACTERIOLOGISTS. 



In the consideration of this topic it is hardly worth while to dip into the ill-digested 

 mixture of fact and speculation published prior to 1874. I shall therefore begin with 

 Sorauer. 



In the first edition of his comprehensive Handbook of Plant Diseases, published in 

 1874, Sorauer makes no mention of bacterial diseases of plants. A great many diseases are 

 included, but none of this type. 



De Jubainville and Vesque writing in 1 878 mention a ' ' cellular rot ' ' of potatoes, radishes 

 carrots, and beets, occuring in the soil or in cellars, but they attribute it to soil ill-adapted 

 to the plants or to improper cultivation. No mention is made of bacteria either as the 

 cause of this rot or of any bther disease mentioned by them. 



There is nothing on this subject in Winter's little book, published in 1878. 



Reinke and Berthold, who published in 1879, found that potato-rot could go on inde- 

 pendently of the presence of fungi. They say: "But there are also wet-rotten potatoes 

 which show no trace of these Pyrenomycetes. " A little farther on we are told correctly 

 that : "A tuber can become wet-rotten without ever having been diseased by Phytophthora.' ' 

 And again. 



It has already been mentioned above that in addition to the Myxomycetes occasionally found 

 upon wet-rotten potatoes, bacteria are also present. In fact, these bacteria are a constant accom- 

 paniment of the wet-rot, and this is an indication as to the true cause of this decay. If a potato- 

 tuber infected by Phytophthora lies in the wet, it passes quickly over into the wet-rotten condition. 

 As soon, however, as the first symptoms of the wet-rot appear, bacteria are found in quantity in 

 the wet-rotten tissue. Notwithstanding this one might think that the Phytophthora caused the 

 wet-rotten decomposition, * * * and that the bacteria hastened the decay only secondarily. 

 But if one inoculates a tuber, which is entirely sound and free from Phytophthora, with the bacterial 

 fluid from a wet-rotten potato, there is always a local production of the wet-rot in the tuber which 

 has been kept moist, and not rarely does it become totally wet-rotten in a very short time. The 

 cause of the wet-rot can be considered to be, therefore, only the bacteria and the ferments produced 

 by them, the tissue of a potato-tuber being only specially predisposed for the action of the bacteria 

 by the Phytophthora. 



