THE AMERICAN 



MONTHLY 



MICROSCOPICAL JOURNAL 



Vol. XIV. 



FEBRUARY, 1893. 



No. 2. 



A Parasitic Fuiigiis (Heterosporiuiu asperatuin) . 



By GEORGE MASSEE, 



LONDON, ENGLAND, 



WITH FRONTISPIECE. 



Abstracted from a paper presented before the Royal Alicr. Society, October ig, 1892. 



This is a common and destructive parasite on the leaves of 

 plants belonging to the order Liliaceoe, and has been observed 

 on plants belonging to the following genera : Convallaria^ 

 Smilacina, S??iilax^ Polygonatuin., and Maianthemum. 



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. Heterosporiunt asperatutn on por- 

 tion ot a leaf oi Smilacina steclata 

 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); «, second- 

 ary spores ; bb, anastomosing 

 hyphje. x 500. 



" 4, 5. Spores germinating in water (80 

 hours); a, secondary spores; b, 

 anastomosing hyphae ; 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 

 secondary 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, x 500. 



" S. Spores germinating in water contain- 

 ing a trace of glycerin, x 500. 



Fig. g. 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. A stout hyphal branch running 

 between the cells of the host-plant 

 and giving off slender branches 

 that penetrate into the cells of the 

 host. X 500. 



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

 mycelium growing 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-plant (80 hours). 

 X 500. 



" 13. A pycnidium produced by stout, 

 dark-colored hyphae 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. 



