מסכת כלים

פרק יט משנה ח

The [leather] shepherd's pouch that was damaged,

the pocket inside of it

is tamei

and is not [considered] connected to it (the novelty of this, as compared to the compartments of the previous mishnah which had the same status, as that the compartments were small boxes by themselves which were then fastened inside the chest; here the pockets are made from a leather patch being sewn by three of its side to the inside wall of the pouch).

The waterskin (made from a piece of an animal's hide)

whose sacs

contain with it (these sacs are actually the scrotum, which were connected to the animal skin that forms the waterskin; rather than cutting it off and having to sew up the hole, they were left in place and held liquids together with the main body of the waterskin)

and they were damaged,

they are tahor

as they do not hold in their usual fashion.  (Some say the part damaged was the main body of the waterskin, and the mishnah is saying that the sacs are tahor, other interpret it the other way around, with the sacs damaged, and the main body of the waterskin consequently tahor.)

A [wooden] chest

that has its opening on its side

can become tamei midras (as it would be sat upon and items could still be put in or taken out of it)

and to the tamei from a corpse;

Rabbi Yosi says

when is this so?

When it is not

ten handbreadths high

and it does not have a rim that is a handbreadth high (as in these cases it would not be sat upon).

If the top was damaged

if the bottom was damaged

Rabbi Meir rules that it is tamei (midras, as it can still be sat upon, even though it can't hold anything)

and the Sages rule it is tahor

as when it's main purpose is eliminated,

its secondary purpose is eliminated.