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XX. 



AWAKD or THE BOYLE MEDAL 



TO GEOKGE H. PETHYBKIDGE, B.Sc, Ph.D. 



192L' 



In submitting the name of Dr. George H. Pethybridge as that of a suitable 

 recipient for the Boyle Medal, the Science Committee have specially in mind 

 his important work in connexion with the elucidation of the life-histor)' of 

 the fungus which causes the potato blight. 



There are, perhaps, few subjects in plant pathology to which so much 

 attention has been devoted as to the potato blight. Eesearch in this field is 

 attractive, not only from a scientific standpoint, but also from a practical and 

 economic point of view. Since its first appearance in the middle of last 

 century, a very considerable mass of literature concerned with this disease 

 has accumulated, emanating from investigators in the laboratories of purely 

 scientific institutions, agricultural stations, and elsewhere. Thus most of the 

 simpler and more obvious features concerning the disease and its causative 

 parasite had been made thoroughly clear long ago, leaving for the new-comer 

 only the more baffling problems to be attacked and solved. 



The fungus itself which causes the potato blight has long been known, and 

 the work of the earlier observers was critically summarized and substantially 

 added to by the important and authoritative reseai-ches of de Bary, 

 culminating in 1876. A vegetative or asexual stage only was known with 

 certainty at that time, and it is during this stage that the parasite plays such 

 havoc amongst the potato plants during the summer, often utterly destroying 

 the foliage and seriously reducing the yield of tubers. Furthermore, it was 

 known that infection spreads from the green parts of the plants above 

 ground, reaches the tubers, and causes them to decay and become practically 

 useless. Exactly how the fungus in the first instance reached the foliage was 

 a problem upon which the investigators of the day were by no means 

 agreed. 



Several closely allied fungi were known which, in addition to possessing 

 a vegetative stage, also produced sexual organs during, or towards the end of, 



' The presentation was made at the Scientific Meeting of the Royal Dublin 

 Society, held on February 22, 1921. 



