SO many inquiries have been made from strangely diverse sources, especially since the outbreak of war, concerning black spots which appear on bell-tents, sails, aeroplane and airship fabrics, etc., that it seemed desirable to write the present note principally to direct attention to a paper by F. Gueguen in Comtes rendus, vol. clix. (1914), p. 781, Sur l'alteration dite piqure des toiles de tente et des toiles a voile. The spots are caused by fungi which damage the fabric, so that after some months it is easily torn. The fungus hyphae grow on the surface of the fabric, between the fibres and within the lumen of the fibres. Gueguen found that the fungi principally concerned were the Pyrenomycetes, Pleospora infectoria and P. herbarum, especially the former. These Ascomycetes are also found in their conidial states, Alternaria tenuis and Macrosporium commune, and other Mucedineae, Rhinocladium, Helminthosporium, etc., are often associated with them. According to Gueguen, the malady is scarcely ever due to accidental contamination, but is caused by the development, in moist warmth, of moulds already present in the newly manufactured fabric, commercial patterns of the most diverse origin being found almost all to contain fungus spores. Practically all unbleached canvas is affected, but that bleached with hypochlorites, etc., remains freethe glaucous colonies which are sometimes seen are due to Penicillium or Aspergillus derived from the air, and almost invariably non-injurious to the fabric. Gueguen holds that the fungi causing the spots ate those which grow on the dead stems of the textile plant, which are introduced amongst the fibres at the time of retting. The thick-walled hyphae remain in a resting state in the dry canvas, and resume vegetative growth when external conditions become again favourable (humidity, warm confined air). He considers that the best method of prevention would be to sterilise the tow after retting, by heatsteam under pressure, and then dry heat. Boiling solutions of salts of chromium or copper would also serve, applied either to the tow or the fabric. A suitable method of rendering awnings, etc., impermeable would be to immerse the fabric first in a 20 per cent. solution of soap, and then in 8 per cent. copper sulphate, each at boiling point.