1. Tumah from a sealed קולית – marrow bone

The next Mishnah states: קולית המת – regarding a marrow bone from a dead body, וקולית המוקדשין – and a marrow bone from a korban [which became נותר], one who touches them, בין סתומים בין נקובים טמא – whether they are closed or punctured, is tamei. Although he cannot touch the marrow inside, the bone of a dead body is itself metamei מדאורייתא, and a bone of נותר is metamei (one’s hands) מדרבנן (to discourage Kohanim from leaving over korban meat). Regarding the marrow bone of a נבילה or שרץ, if they are completely closed, one who touches them is tahor, but if they are punctured even a minimal amount, one who touches them is tamei (even without touching the marrow itself). Since he can touch the marrow (by inserting even a hair through the hole), the bone can transmit the marrow’s tumah as a שומר. The Mishnah concludes that a sealed bone cannot even convey tumah through משא – carrying, because משא is written next to מגע, teaching: את שבא לכלל מגע בא לכלל משא – that which enters the category of tumah through touching also enters the category of tumah through carrying, but that which cannot be metamei through מגע is also not metamei through משא.

1. Can a קולית be metamei through אהל?

The Mishnah states that the marrow bone of a dead body is metamei with מגע, implying that it is not metamei through מאהיל – one who forms a roof over it. Accordingly, the bone must have less than a כזית of flesh. Furthermore, it cannot contain a כזית of מוח – marrow inside, because such enclosed tumah is בוקעת ועולה – breaks through its covering (the bone) and rises, and would be metamei through אהל. Finally, the Gemara asks: if מוח מבפנים מעלה ארוכה מבחוץ – marrow inside a living creature’s bone can regenerate flesh outside the bone, אבר מעליא היא – [the bone] is considered a full-fledged limb, and should be metamei with אהל!? There are three approaches to this question: (1) Rav Yehudah brei d’Rebbe Chiya says that this Mishnah teaches that inner marrow cannot regenerate outside flesh. (2) Abaye disagrees, and explains that the Mishnah’s case is בששפה – where he scraped away part of the bone so it can no longer regenerate flesh. (3) Rebbe Yochanan says there is a כזית of מוח in the bone, and it is metamei with אהל; this is included in the Mishnah’s term "נוגע" – touching.

1. Rope meshwork within a tefach above a מת

Rebbe Yose says that חבילי מטה וסריגי חלונות – the interlaced ropes of a bed and the [interlaced bars] of a window can form a חציצה between a lower and upper floor. Thus, if a מת is on the lower floor and someone on the upper floor touches the space opposite the holes in the meshwork, he remains tahor. However, if the ropes were spread out in the air over a מת, one who touches the space opposite the holes becomes tamei through אהל, because the ropes do not form a חציצה between the floors when they are not part of the structure. Rava maintains that if the ropes were spread within a tefach above the מת, it would be tantamount to מת בכסותו – a body in its garment, which transmits tumah with אהל; here too, even placing one’s hand opposite the ropes themselves should make him tamei through אהל. Rather, the ropes must be spread more than a tefach above the מת. Abaye disagrees and says that even if the ropes are within a tefach of the מת, they are different from a מת’s garment: מת בכסותו מבטל ליה – regarding a body in its garment, he designates [the garment] for the body, whereas he is not מבטל ropes suspended above the body.