ILLUSTRATIONS OF PHYTOPHTHORA INFESTANS. 413 



Illustrations of the Structure and Life-History 

 of Phytophthora infestans, the Fungus 

 causing the Potato Disease. 



By 



H. marsball ITard, 9I.A., F.Ii.S., 



Fellow of Christ's College, Cambridge, and Professor of Botany in the 



Forestry School, Royal Indian College, Cooper's Hill. 



With Plates XXXI and XXXII. 



Some time ago I was commissioned to prepare for the 

 Science and Art Department, South Kensington, a series of 

 drawings illustrating the structure and life-histories of certain 

 parasitic fungi; the intention being that these drawings should 

 eventually be enlarged to form wall-diagrams suitable for 

 museum and teaching purposes. I soon found that if the 

 drawings were to be what I should wish them to be — i. e. to 

 form a properly connected series, and to be taken from original 

 preparations — the task promised to develope into one of greater 

 magnitude than had been anticipated. In fact it became 

 necessary to go over the entire field. 



On the completion of the drawings from which the diagrams 

 illustrating the phenomena in the life of the potato disease 

 fungus (Phytophthora infestans) were to be selected, it 

 was suggested to me that they form in themselves a series 

 which would probably be welcomed as bringing together facts 

 about this fungus in a connected form, whereas what other 

 original figures exist are scattered through various foreign 

 periodicals, &c., or are not easily accessible to students. 



The text, it will be noticed, applies to the drawings through- 



