1,048,761. Desiccating biological substances. LABORATOIRES DE RECHERCHES EXPERIMENTALES GOULDEN CIE. Dec. 31, 1962 [Nov. 29, 1961], No. 42686/61. Heading A2D. Physically and chemically fragile biological substances are desiccated with their active constituents being left substantially unchanged, by diffusion of water vapour through an artificial vapour-permeable enclosure around the substance consequent upon a removal of water vapour from the medium surrounding the enclosure, under ambient conditions of temperature and pressure, creating a vapour pressure difference as between the interior of the enclosure and the surrounding medium, proportioned quantities of the biological substance being brought into a condition permitting the flow of water vapour into the surrounding medium. When the surrounding medium is a confined atmosphere, the water vapour may be removed by means of a desiccating agent such as silica gel or calcium chloride. Alternatively, the water vapour in a circulating atmosphere may be removed by freezing. Hypophysis glands and other animal tissues, leaves of medicinal plants and other vegetable tissues, pumpkin seeds, and cytochrome and other opotherapic extracts may be desiccated. The enclosures may consist of sterile envelopes of "Cellophane" (Registered Trade Mark), paper bags, unglazed eathernware pots and porous Chamberlan filters.