280 the president's address. 



a fanciful analogy, but it seems to me that there are striking coinci- 

 dences in the advent and spread of these contagious diseases, 

 whether affecting animals or plants. Even in some of the minor 

 details affecting the dispersion of the disease the analogy is con- 

 tinued. We seem to be reading, between the lines, of some malignant 

 fever, or of some animal contagion, when we read of the conditions 

 favourable to, or opposed to the spread of plant epidemics.* 



Alluding to the hollyhock disease, a writer says (" Gard. Chron.," 

 Aug. 22nd, 1874, p. 243), " I believe planting the hollyhock in 

 large crowded beds should be avoided, as I have observed the closer 

 they are growing the more virulently does the disease attack them, 

 whereas isolated rows and plants are but little injured." 



The Inspectors of Fisheries, in their Eeport (1880, p. 19.), quote 

 the following evidence given before them : — " The river is over- 

 stocked, so is every river where there is a fungus. It is a symptom 

 of overstocking. Rivers will only carry a certain amount of fish ; 

 when you get beyond this, the disease apj)ears." In addition to 

 evidence the following opinion is expressed by the Inspectors them- 

 selves (p. 20.) : — " In confirmation of the fact that overcrowding of 

 fish will produce fungus growth, it is important to note that (as all 

 breeders of salmon by artificial means know only too well) when 

 the young of Salmonidce have attained a certain growth if they are 

 too crowded in the hatching trough, they at first breathe with great 

 difficulty, and ultimately die with the gills propped widely open 

 by a growth of fungus. If the fish are allowed to remain in the 

 water in a few hours the fungus will spread completely over the 

 whole of the body, growing equally from all parts of the body, so 

 that finally it assumes the appearance of thistle-down." 



observed in Ireland (" Gardeners' Chronicle," 1845, p. G74), but the great 

 outbreak was in 1844 and succeeding years. It was known in Canada and 

 some of the United States in 1844, in Saint Helena in the same year, and 

 then first appeared in the Isle of Thanet (Berkeley in " Hort. Journ.", i., p. 

 12). In 1845, on the 16th August, it was seen in the Isle of Wight; on 

 the 23rd August in the south of England generally ; but up to the 30th was 

 still unknown in the Midland counties. By the 7th September it had shown 

 itself in Ireland, and later in the year in Scotland. The history of its early 

 progress is recorded by Rev. M. J. Berkeley "On Potato Murrain," in 

 " Journ. of Royal Hort. Society," Vol. i. for 1846. 



* " "When the array of diseases produced by fungi, which, formerly un- 

 noticed, have, in later times, attracted universal attention by their destruc- 

 tive consequences, is surveyed, it might readily be supposed that, as in the 

 diseases to which the human frame is subject, every period has its pre- 

 vailing character, so also, in the vegetable kingdom, certain variable and 

 secular influences prevail, to which is to be ascribed the circumstance of 

 the present activity of diseases produced by fungi." — Braun, " On Diseases 

 of Plants," " Quart. Micro. Journ.," 1854, p. 253. 



