THE AMERICAN 



MONTHLY 



MICROSCOPICAL JOURNAL 



Vol. XIV. 



FEBRUARY, 1893. 



N... 2. 



A Parasitic Fuiiiriis (Helcrosporiniii asperatuin). 



By GEORGE MASSEE, 



LONDON, ENGLAND, 

 WITH FRONTISPIKCE. 



Abstracted from a paper prcsenteJ befcre the Royal Mitr. .Society, October 19, 1892. 



This is a common and destructive parasite on the leaves of 

 phints belon<2[iii<2^ to the order LiliacciTJ, and has been observed 

 on phnits belonging to the following genera : Convallaria^ 

 Smilacitia^ S/ni/ax^ Polygonatuni^ and Maiattthcnnnn. 



In common with many parasites, the fungus does not appear 

 on the surface until the leaf becomes more or less dry and dis- 

 colored, and on this account its presence has been considered by 

 some as the result rather than the cause of the disease : but in 

 '•eality the vegetative mycelium is present in the tissues of the 

 leaf for some time before there are any external signs of its 

 presence. 



In Smilacina stellata, as in the other host-plants of the 

 fungus, the tip of the leaf has a slight oblique twist that retains 



Explanation of Plate. 



Fig. 



I. Htterosporiuitt asperatum on por- 

 tion of a leaf o{ Smilacina steilata 

 Desf. , nat. size. 

 \a and 2. Spores germinating in a steril- 

 ized solution of the host-plant (20 

 hours). X 500. 



3. Spores germinating in a solution of 



the host-plant (48 hours); a, second- 

 ary spores ; bb, anastomosing 

 hyphi. X 500. 



4, 5. Spores germinating in water (80 



hours): a, secondary spores; b, 

 anastomosing hyi hae ; c, a hyphal 

 branch that has formed a loop by 

 curving and anastomosing with the 

 parent hypha. x 500. 



6. Old sporophores that have produced 



seconi.'ary spores after remaining in 

 water for four days ; a, secondary 

 spores ; b, sporophores. x 500. 



7. Spores germinating in a solution of 



leaf of sunflower ; a, sessile whorls 

 of secondary spores. .\ 500. 

 R. Spores germinating in water contain- 

 ing a trace of glycerin, x 500. 



Fig. 9. A fascicle of sporophores bearing 

 spores; a, the sclerotioid base from 

 which the sporophores spring ; b, 

 a portion of the hypha; that pro- 

 duce the sclerotioid base, x 500. 



" 10. K stout hyphal branch running 

 between the Crlls of the host-plant 

 and giving ofT slender branches 

 that penetrate into the cells of the 

 host. X 500. 



" II. A stout, dark-coIor;d portion of 

 mycelium grovviig in a dead leaf, 

 and bearing two sclerotia. .\ 500. 



" 12. A sclerotium producing secondary 

 spores in a solution of the dead 

 leaves of the host-p'ant (So hours). 

 X 500. 



" 13. A pycnidium produced by stout, 

 dark-colored hyphas in a dead leaf 

 of the host-plant, x 500. 



" 14. Section of a portion of the wall of a 

 pycnidium, showing the origin of 

 the pycnospores. x 500. 



