228 AGRICULTURAL EXPERIMENT STATION. [Jan. 



leave, fearing that its appearance was an indication of the 

 unhealtlifuhiess of the premises. 



It was evident to the unaided eye, and microscopic exam- 

 ination confirmed the opinion, that the white material was 

 the sterile mycelium of some fungus. As there was no trace 

 of spore formation, it was impossible to say to what fungus 

 the mycelium belonged, though more probably to some 

 member of the toadstool group. 



The only conditions necessary to the development of such 

 mycelia are the presence of spores, and of certain degrees 

 of temperature and moisture. The latter conditions are 

 afforded by even the best of cellars, which receive no arti- 

 ficial heat, and fungus spores penetrate ever}^ crevice with 

 the air in wdiich they float. Not only are such growths 

 perfectly harmless in themselves, l)ut their occasional 

 appearance is no indication of unhealthful conditions ; 

 although their very constant or luxuriant appearance is 

 often an accompaniment of extreme dam})ness. For the 

 sake of neatness, it is best to remove them with rake or 

 broom, and prevent their reappearance on the same surface 

 by the free application of lime, either dry or in the form of 

 whitewash. 



A report to this effect was made in the present case, but 

 it was afterwards learned that the tenants had already 

 left, victims to their superstitious fears and dread of the 

 " mysterious." 



It should be remarked here that the appearance' of white 

 fungus mycelia, followed by the development, on the surface 

 of the mass, of a rusty-l)rown spore layer, with the exuda- 

 tion of watery drops at its margin, should receive prompt 

 attention. The fungus wdiich answers to this description 

 belongs to the toadstool group, and appears on w^oodwork 

 or even on cellar l)ottoms. It produces a very rapid and 

 destructive " dry rot " of timber, and is known in Germany 

 as the " house fungus." It should be thoroughly destroyed, 

 and all woodwork in its vicinity painted or well whitewashed. 



2. Blach Spot of Rose Leaves. — A disease affecting the 

 leaves of roses growing in the Durfee plant-house of the 

 Massachusetts Agricultural College was referred by Prof. 

 S. T. Maynard to this department for examination and 



