469 



[September 30th, 1896, contd.] 



THE SOOTY MOULD OF CITRUS TREES : A STUDY 

 IN POLYMORPHISM. 



(Capiiodium citrico/um, n.sjx) 



By D. McAlpixe. 



(Communicated hy J. II. Maiden, F.L.S.) 



(Plates XXIII. -xxxiv.) 



CONTENTS. 



PAGE 



Introductory ... ... ... ... 469 



Source of Specimens Investigated — 



Doncaster Specimens ... . ... 471 



Armadale ,, ... .. ... 4S1 



Kew ,, 482 



Burnley „ 482 



Other Victorian „ 483 



South Australian ,, ... ... ... 483 



New South Wales ,, 483 



General Development of Spf)ridia in Asci ... ... 485 



Characteristic Distinctions of the Special Repro- 

 ductive Bodies ... .. ... ... ... 486 



Connection with Scale or other Insects ... •• ... 487 



Effect on Trees 490 



Treatment 490 



Scientific Description ... ... ... ... ... 491 



Polymorphism ... ... ... ... ... ... 493 



Appendix on Microcera coccophila, Desm. ... ... 498 



This disease has been known for a long time, chiefly in Southern 

 Europe, and now wherever Citrus trees are grown. It has had 

 various common names in different countries, such as " Morfea," 

 "Fumago," "Nero" in Italy; "Russthau or Sootdew" in Germany; 

 "Sooty Mould" in Florida; and " Fumagine," "Black Mildew," 

 32 



