1897.] 



PUBLIC DOCUMENT— No. 33. 



69 



marked by concentric curved lines parallel to the edge of 

 the dead portion, as in many spot diseases of fungous origin. 

 ]\licroscopic examination, however, shows nothing which 

 may with certainty be decided upon as the cause of the 

 trouble. "We usually find fungous filaments and spores, but 

 they are of many dif- 

 ferent species, and 

 mostly moulds of a 

 saprophytic or only 

 partially parasitic 

 nature, and cannot 

 be regarded as the 

 primary cause of the 

 disease. In a few 

 specimens we have 

 found the spore- 

 bearing conceptacles 

 and spores of a fun- 

 gus belonging to or 

 near the extensive 

 parasitic genus Gloe- 

 osporium, which in- 

 cludes a great num- 

 ber of leaf spots. 

 AVe consider this as 

 the probable cause of 

 the disease, but the 

 spore-bearing mate- 

 rial was very scanty, 

 and we were unable to identify it with any described speci-es. 

 Possibly the trouble may be due to various causes, not all of 

 a fungus nature, but appearances seem to indicate that there 

 is a definite disease which causes most of the spotting. At 

 all events, it will be a wise precaution, in this and all similar 

 cases, to remove and burn all affected leaves. 



Several other leaf spots of the palm, dracaena, ficus and 

 other decorative plants have come to our notice. Some were 

 only simple sun-burns, while others were real fungous dis- 

 eases. What was at first thought to be Leptostromella 

 elastica (the above-described leaf spot on Ficus elastica) 



Fig. 4. — Pilobolus crystallinus, Tode. 

 I. Somewhat enlarged. 

 II. Sporangia on rose leaflet. 

 II. Discharge of sporaugium. 



V^. Section of sporangium and filament, showing spores, 

 v. Sporangium upon filament before being discharged. 

 III., IV. and v. are greatly enlarged. 



