RESEARCH IN PHYTOPATHOLOGY 193 



plants, which later researches have so completely established. 

 He demonstrated the complete breaking down of the cellulose 

 wall by experiments upon the cells of the potato, and, as his 

 material contained no trace of any fungus, he suggested that the 

 " vibriones " which were present in great abundance must be 

 the agents responsible for the phenomenon. In 1865 Trecul, in 

 the course of his researches upon laticiferous vessels, observed 

 the appearance of minute bodies in the tissues under examination 

 which seemed to him to arise quite suddenly and spontaneously 

 in the laticiferous vessels and closed cells. These bodies, 

 which he termed Amylobacter, furnished him with an argument 

 in favour of spontaneous generation, only disposed of when, 

 later, van Tieghem showed them to be stages in the development 

 of a bacillus, named by him B. amylobacter^ identical with 

 the " vibriones" which Mitscherlich had rightly supposed to be 

 the active agents in the dissolution of cellulose. Later, in the 

 year 1879, van Tieghem carried out some investigations im- 

 portant for that day upon the action of bacteria as agents in the 

 destruction of cellulose, and he clearly showed that certain 

 bacteria possess the remarkable property of dissolving cellulose, 

 but he was undoubtedly working with mixed cultures and was 

 mistaken in attributing his results specifically to B. amylobacter. 



In 1878 Burril traced a disease known as Pear Blight or 

 Fire Blight, which produced a blackening of the parts affected 

 and a gummy exudation, to the attack of a micro-organism. 

 Micrococcus ainylovorus. He found no sign whatever of fungoid 

 growth in the diseased tissues until after the death of the cells 

 and he succeeded in communicating the disease by a series of 

 inoculations by direct infection from the diseased to healthy 

 tissues. 



This paper was followed in 1879 by Prillieux's description of 

 the Pink Discoloration of Wheat due to a Micrococcus ; these 

 two represent the very first accounts of any disease of plants 

 definitely attributed to bacteria. 



Prillieux made a very close observation of the microscopic 

 features of the disease of the wheat, which was invariably 

 associated with the presence of Micrococcus tritici. He noted 

 their destructive action upon the elements constituting the 

 grain, the corrosion first of the starch-grains, then the proteids, 

 and also the dissolution of the cellulose but he made no cultures 

 or attempts at inoculation. 



