THE DISEASES OF BOOKS — Various agents of a physical and biological nature can modify, to a greater or lesser extent, the structure of writing materials, causing alterations that may resemble diseases, due to certain affinities with the morbid states typical of plant and animal organisms. Their onset can be prevented through appropriate prophylaxis, or their progress and development can be halted by promptly adopting remedies suited to the nature of the processes to be combated.
Climatic factors, that is, the complex of conditions involving humidity, temperature, pressure, aeration, and insolation, can alone provoke these alterations if they exceed certain maxima or minima, or they can favor the spread of harmful biological species. When speaking of climate, reference is made to that of the environment in which books are preserved, not to any single one of its agents but to all of them and their mutual relationships. Indeed, to ensure that library materials remain in a hygienic state of preservation, the average temperature should not exceed 18° to 20° C., provided that the relative humidity does not fall below 40% or rise above 65%. Beyond these limits, fibers, fabrics, and adhesives suffer from the excesses and deficiencies of humidity. The same applies to permanent imbalances in the other factors. Insects, molds, and bacteria thrive and propagate more easily when they encounter temperatures and humidity levels above the aforementioned averages.
Thus, a tradition of studies has developed in which the causes, origins, and pathological manifestations of these phenomena, as well as the means to prevent and combat them, are investigated. Among biological agents, the human being stands foremost, for as both the creator and user of books, he knowingly or unknowingly inflicts potential or actual, direct or indirect damage upon them. Since ancient times, accounts have existed of voracious insects that damage books and shelves. However, only since it has become possible to distinguish species from one another, to study their habits and biological capabilities, have prophylactic measures been adopted to prevent their spread, and in cases of infestation, interventions have been devised to ensure energetic and rapid disinfection.
Almost all alterations of a microbial nature (pigmentations, downy and granular growths of various colors, etc.) are commonly referred to as molds. Many of these are indeed due to the specific action of fungi, now merely chromogenic, now
studies its history in relation to writing materials and instruments, to printing techniques, to ornamentation (v. MINIATURE), to binding (v.), but it also addresses the damage and restoration, as well as editorial techniques.
On the applications of microfilm, cf. the report of the conference by Fr. Anselmo M. Albareda held on 25 Nov. 1948 at the Vatican Library, in *L'Osservatore Romano*, 1 Dec. 1948, p. 2, cols. 1-2. — For the diseases of books cf. A. Gallo, *Le malattie del l.*, Milan 1935; id., *Patologia del l.*, in *Bollettino dell'Unità di patologia del l.*, 8 (1949), pp. 1-55 (with bibliography). Alfonso Gallo