A chest whose opening is on its side [can become] tamei with midras tumah and with corpse-tumah. R’ Yose says: When is this so? When it is not ten handbreadths high, and it has no rim [of] one handbreadth. If [the chest] became damaged at [its] top, it [can become] tamei with corpse-tumah. If it became damaged at [its] bottom, R’ Meir rules it tamei. But the Sages rule it tahor because [when] the primary [function of a utensil] is disabled, [its] secondary [function] is [considered] disabled [as well].