A method of preparing a reagent solution, the method comprising: providing a plurality of enclosures (110, 610, 1128) within a volume of a cartridge, the cartridge including a gas port, and each enclosure including: a container (120, 620, 1130) disposed within the enclosure (110, 610, 1128), the container (120, 620, 1130) defining an internal cavity (320, 820) and defining a passage (330, 830) providing fluidic communication between the internal cavity (320, 820) and the exterior of the container (120, 620, 1130) and comprising a compressible volume disposed within the internal cavity (320, 820); and a reagent disposed within the internal cavity (320, 820), a fluid port (130, 630) providing fluid access to the interior of the enclosure (110, 610, 1128); filling the enclosures (110, 610, 1128) with a fluid through the fluid port (130, 630) of the enclosures (110, 610, 1128); increasing a gas pressure of the volume of the cartridge via the gas port to pressurize the fluid within the enclosure (110, 610, 1128), the fluid flowing into the internal cavity (320, 820) of the container (120, 620, 1130) and compressing the compressible volume; and decreasing the gas pressure of the volume of the cartridge via the gas port to depressurize the fluid within the enclosure (110, 610, 1128), the compressible volume decompressing and ejecting the fluid and reagent from the internal cavity (320, 820), the reagent mixing with the fluid, wherein the enclosures (110, 610, 1128) are flexible enclosures and wherein pressurizing includes increasing a gas pressure external to the flexible enclosures. providing a plurality of enclosures (110, 610, 1128) within a volume of a cartridge, the cartridge including a gas port, and each enclosure including: a container (120, 620, 1130) disposed within the enclosure (110, 610, 1128), the container (120, 620, 1130) defining an internal cavity (320, 820) and defining a passage (330, 830) providing fluidic communication between the internal cavity (320, 820) and the exterior of the container (120, 620, 1130) and comprising a compressible volume disposed within the internal cavity (320, 820); and a reagent disposed within the internal cavity (320, 820), a fluid port (130, 630) providing fluid access to the interior of the enclosure (110, 610, 1128); a container (120, 620, 1130) disposed within the enclosure (110, 610, 1128), the container (120, 620, 1130) defining an internal cavity (320, 820) and defining a passage (330, 830) providing fluidic communication between the internal cavity (320, 820) and the exterior of the container (120, 620, 1130) and comprising a compressible volume disposed within the internal cavity (320, 820); and a reagent disposed within the internal cavity (320, 820), a fluid port (130, 630) providing fluid access to the interior of the enclosure (110, 610, 1128); filling the enclosures (110, 610, 1128) with a fluid through the fluid port (130, 630) of the enclosures (110, 610, 1128); increasing a gas pressure of the volume of the cartridge via the gas port to pressurize the fluid within the enclosure (110, 610, 1128), the fluid flowing into the internal cavity (320, 820) of the container (120, 620, 1130) and compressing the compressible volume; and decreasing the gas pressure of the volume of the cartridge via the gas port to depressurize the fluid within the enclosure (110, 610, 1128), the compressible volume decompressing and ejecting the fluid and reagent from the internal cavity (320, 820), the reagent mixing with the fluid, wherein the enclosures (110, 610, 1128) are flexible enclosures and wherein pressurizing includes increasing a gas pressure external to the flexible enclosures.