136 



"Famine forces Peel's hand" is a 

 chapter heading in McCarthy's Ilis- 

 tory' of our Own Times. Sir Robert Peel 

 was Prime Minister of luigland when 

 the terrible murrain devastated the 

 potato fields of Ireland and destroyed 

 the country's food. The epidemic itself 

 is important in the history of plant 

 pathology, for it intensified efforts to 

 find out what caused the blight. But 

 its social consequences loom large in 

 the recent histor)' of Britain and far 

 beyond. Wheat rust had impelled legis- 

 lation against an accessory to the dis- 

 ease, but the potato blight was a de- 

 cisive accessory to legislation for social 

 reform. It helped put an end to the 

 protective tariff on imported grain, the 

 so-called cruel Corn Laws, 



News came from Ireland in the au- 

 tumn of 1845, that potato blight 

 threatened to destroy "the food of a 

 people." Tlie Relief Committee of 

 Dublin demanded that the ports be 

 opened to free entry of grain and de- 

 nounced the Ministry for its inaction. 

 The Anti-Corn-Law League also was 

 clamoring for the removal of restric- 

 tions on the importation of grain. And 

 still the Conservative Cabinet did noth- 

 ing, except appoint an anti-famine com- 

 mission. But Lord John Russell, leader 

 of the opposition Whigs, wrote to some 

 of his constituents that "Indecision and 

 procrastination may produce a state of 

 suffering which it is frightful to con- 

 template. . . ." Potato blight had con- 

 verted him to the principles of the 

 League. This forced Peel's ministry to 

 introduce a bill for the virtual abolition 

 of the laws, and, after various vicissi- 

 tudes, it was enacted into law in the 

 summer of 1846. Britain was on the 

 way to free trade. 



Thus did a plant disease force re- 

 forms which may other\vise have been 

 long delayed; the potato famine was 

 too tragic for politicians to ignore. 

 Whatever the true number of deaths, 

 it is certain that Ireland quickly lost 



LOWER PLANTS, DISEASES, AND MEDICINE 



two million of her eight million people, 

 from starvation, consequent disease, 

 and emigration. 



Plant diseases have indeed played 

 an important role in the social develop- 

 ment of the world. 'Ilieir greatest single 

 contribution, of course, was the science 

 of plant patliology itself. Society sired 

 the science because it wanted help, and 

 the science is doing its filial duty by 

 helping with the chores and with the 

 education of its sire. Exactly when 

 plant pathology was born is a moot 

 question; why it was born is no ques- 

 tion at all. It was bom of necessity. 



For better or for worse, plant pa- 

 thology had its genesis in fields and 

 granaries more than in halls of ivy. 

 Society needed agriculture and agricul- 

 ture needed plant pathology. Of 

 course plant disease excited curiosity, 

 but the curiosity was more excited be- 

 cause the diseases struck in vital spots, 

 the breadbaskets and the fields that 

 filled them. It was essential to social 

 progress that the baskets be filled, and 

 men of scientific bent tried to fill them. 

 Not until the microscope was in- 

 vented could there be a science of plant 

 pathology based on understanding. 

 Micro-organisms had been postulated 

 long before but they could not be 

 proved. Even the practical Varro stated 

 as simple fact that minute invisible 

 creatures were bred in swamps, were 

 carried by the wind, and, when inhaled, 

 caused serious diseases of humans. One 

 can only speculate about what Varro 

 might have discovered with the micro- 

 scope. 



The microscope, from about 1590 

 onward, was ready to reveal an entirely 

 new world to those who would look for 

 it. Not until a century and a half had 

 passed, however, was it used systema- 

 tically to elucidate the nature of plant 

 diseases, for most botanists were pre- 

 occupied with other problems. The 

 basis for a real revolution in concepts 

 about disease was laid by three brilliant 



