NOTES OX RECENT RESEARCH. 



717 



Vaccination applied to Plants. 



Vaccination Of Vegetables. By Raymond Roger {Rev. Hort. 

 pp. 340-342 ; July 16, 1902). — In lieu of attacking contagious plant 

 diseases by means of disinfectant solutions or vapours with a view to the 

 destruction of existing organic germs, it is suggested as possible to 

 anticipate the attacks of the mora destructive types of thes3 by prior 

 infection by less harmful ones on the antitoxin principle. It is pointed 

 out that disinfectants of the class named are powerless where the pest 

 has already invaded the internal tissues, and that hence the remedy is 

 only partial, while such a remedy as the one in view would render the 

 plants immune from such internal disintegration by weakening the force 

 of the invading and disease-producing micro-organisms. The questions 

 are raised, Do the parasitic micro-organisms secrete toxines in vegetable 

 tissues as their co-generic fellows do in animals ? Is the damage caused 

 by their presence in the body of the plant due simply to the exhaustion 

 by these foreign intruders of a part of the elementary matter destined 

 for the plant itself, arid hence causing an ana?mia, or is the matter com- 

 plicated by a veritable poisoning by toxines or noxious secretions of the 

 parasite ? As little evidence has been gathered on this point we can only 

 argue by analogy, which teaches us that the success of vaccination depends 

 in most cases on the production in the parasitic micro-organism of 

 elements noxious to the parasite itself which render the subject immune. 

 Observation so far tends to confirm this idea as regards plants. It is well 

 known that the yeasts of fermented liquors, for instance, belonging to 

 fungi of the Saccharomyces or Mucor genera sown in media rich in 

 saccharine matter, have their vitality suspended so soon as the alcoholic 

 contents attain a certain degree, although a large quantity of the sugar 

 may not yet have suffered decomposition. Their activity is annihilated 

 by the presence of the alcohol, a true toxine secreted by themselves. 



More precise facts resulting from recent experiments by M. J. 

 Beauverie permit of the assumption in other cases, not only of the 

 production of toxines, but also of the possibility of attenuating the 

 virulence, and thus lead up to the hope that at length vegetable pathology 

 may benefit by Pasteurian methods of imparting immunity. 



The marvellous results of his researches into the life history of the 

 microbe of plant rot {la to He), Botrytis cinerea, by turning attention to 

 this branch of investigation, will form beyond doubt the starting-point of 

 a new therapeutical method as applied to vegetable diseases. 



We set forth briefly the facts as presented by M. Gaston Bonnier to 

 the Academy of Science at the meeting of July 8, 1901. According to 

 M. J. Beauverie, Botrytis cinerea, or the plant-rot microbe, presents itself 

 under three different forms, according to the conditions of the medium in 

 which it is developed. 



(a) Under its normal form it is saprophytic, i.e. it lives at the 

 expense of organic matter in decomposition. This condition, under 

 which it is absolutely harmless to living vegetation, is characterised by 

 the appearance of conidia as reproductive organs. 



(b) When Botrytis cinerea is developed under conditions of saturated 

 humidity at a temperature of about 30° C. it becomes sterile, does not 



