278 the president's address. 



diseases in plants, as well as in animals, although sometimes it 

 would seem that theorists entirely forget the circumstance, or prac- . 

 tically ignore it. The twelfth chapter of Darwin's " Variation of 

 Animals and Plants Under Domestication " seems for the time to be 

 forgotten. Whilst inheritance of insanity, gout, epilepsy, consump- 

 tion, asthma, cancer, &c, are admitted in the human subject, and 

 other diseases in lower animals, insufficient importance is attached 

 to the same tendency in plants. It must now be tolerably clear to 

 most minds that something of the potato disease, the hollyhock 

 disease, and even the wheat-mildew, will be due to inheritance. It 

 would be folly to deny such a probability. The fact has been before 

 quoted that celery plants, raised from the seed of plants greatly 

 infected with the celery disease {Puccinia apii) were similarly in- 

 fected though growing in the same garden, at a few yards distance 

 from perfectly clean plants grown from the seed of uninfected 

 parents. Instead, however, of permitting themselves to think of 

 hereditary transmission, some authors have indulged in fanciful 

 speculations as to the inoculation of plants with certain diseases, 

 as if they had no parents with diseases to transmit, or were wholly 

 incapable of transmitting them. In the face of the marvellous 

 changes which the Florist and Pomologist has produced in our 

 cultivated flowers and fruits by taking advantage of this very 

 powerful tendency of inheritance, it is passing strange that any 

 should ignore such agency for a remote speculation, which has no 

 equivalent support from experience or analogy. 



The Rev. M. J. Berkeley has thus written : — 



tl There is something extremely capricious in the attacks of these 

 diseases amongst plants, exactly as is the case with infectious 

 maladies amongst ourselves. One is taken and another left with- 

 out our being able to account for it, nor is it probable that we shall 

 ever penetrate these mysteries, which baffle all our efforts, and re- 

 mind us of our true position in the scale of intelligent beings. 



" A perennial plant or tree once attacked by parasites seldom 

 gets perfectly free from the disease, and there may be a greater 

 analogy in the peculiar liability of certain constitutions to the recur- 

 rence of such maladies as influenza, to the fact that in the present 

 state of our knowledge as to the cause of disease we should at pre- 

 sent be willing to allow. A plant of Achillea ptarmica was given 

 to us at Lille, in the month of March for the express purpose of 

 bearing a crop of Labrella Ptarmicce the ensuing autumn, which it 



