APPENDIX 1. 



Distribution and extension of some jmrasitic bacteria and fungi, chiefly those 

 causing diseases of cultivated plants. 



The records below contain the brief history of the spread of most of the 

 important cryptogamic diseases of cultivated plants whose extension has 

 attracted notice during the past 70 years, before which there is little informa- 

 tion available. It has been impossible to verify all the references with the 

 facilities at my disposal, and in any case it must be understood that the 

 published record of the appearance of a disease often does not occur for a 

 year or more after the parasite has actually been introduced, even in the more 

 advanced countries, while for much of Asia and Africa the date of record gives 

 no indication of when the parasite was introduced. A tliorough search 

 through herbarium specimens would doubtless result in putting back the 

 date of the appearance of several of the diseases referred to in different 

 countries, but even then we would not always have an exact date for the 

 introduction of the parasite. Hence the records must be taken usually as 

 giving an approximate picture of the spread of a disease and are open to 

 correction on further enquiry. 



