PHYTOrHTHOKA. 



119 



Another parasite of conifer seedlings — Fusovio. 2)arasiticmn — 

 which somewhat resembles Phyfophfhora, is figured and described 

 amongst the " Fungi imperfecti." 



Phytophthora infestans, l)e Bary.^ This parasite was first 

 observed in Kuro^te in 1845, and has since then become 





FiO. 29. 



Fio. 30. 



Fig. 20.— Cellular tis.suc from diseased cotyledon of Beech. The starch-grains 

 have been absorbed from the cell-protoplasm which has shrunk awaj- from the 

 cell-wall a ; b, (>, intercellular fungal hyphae with very tiny haustoria ; c, c, 

 fertilized oogonia, each containing a .single oospore. (After K. Hartig.) 



Fio. 30.— Phi/tojihlhora omnii-ora on the epidermis of a Beech -cotyledon, c. 

 Outer wall of epidermal cell; li, cuticle; c, hyphae growing between cell-wall 

 and cuticle, causing the shght protuberance d; e, spot where a hypha has 

 emerged through the cuticle and developed as a sporangiophore/; after the first 

 sporangium has reached maturity a second begins to form, n atid h, whereby the 

 first is displaced ; A-, a stoma from which sporangiophores have developed. 

 (After R. Hartig.) 



only too well known. It attacks leaves, shoots, and tubers 

 of potato and other Solanaceae, e.g. the tomato (S. Li/copersicum). 

 The potato leaves become discoloured, brown-spotted, and 

 crumpled, especially in damp weather. The sporangiophores 

 (gonidiophores of De Bary) issue from tlie stomata in 



1 De Bary, Journal of Botany, 1876, and Journal of the. Royal Agrir. Society, 

 1876. 



