Halacha

הלכה א
הַנֵּפֶל אַף עַל פִּי שֶׁעֲדַיִן לֹא נִתְקַשְּׁרוּ אֵיבָרָיו בְּגִידִין מְטַמֵּא בְּמַגָּע וּבְמַשָּׂא וּבְאֹהֶל כְּאָדָם גָּדוֹל שֶׁמֵּת שֶׁנֶּאֱמַר (במדבר יט יא) "הַנֹּגֵעַ בְּמֵת לְכָל נֶפֶשׁ אָדָם". וְכֵן כְּזַיִת מִבְּשַׂר הַמֵּת בֵּין לַח בֵּין יָבֵשׁ כְּחֶרֶשׂ מְטַמֵּא כְּמֵת שָׁלֵם. וְהַנֶּצֶל בַּבָּשָׂר מְטַמֵּא בִּכְזַיִת. אֵיזֶהוּ נֶצֶל זֶה הַבָּשָׂר שֶׁנִּמּוֹחַ וְנַעֲשֶׂה לֵחָה סְרוּחָה. וְהוּא שֶׁתִּקְרשׁ אוֹתָהּ הַלֵּחָה הַנִּמְצֵאת מִן הַמֵּת שֶׁאִם קָרְשָׁה בְּיָדוּעַ שֶׁהוּא מִבְּשָׂרוֹ וְאִם לֹא קָרְשָׁה אֵינָהּ מְטַמְּאָה שֶׁמָּא כִּיחוֹ וְנִיעוֹ הוּא:
כסף משנה
1.
A stillborn fetus, even though it is underdeveloped and its limbs have not been firmly connected with their sinews, imparts ritual impurity when it is touched, carried, or when one is under the same structure as it, like the corpse of an adult that has died, as implied by Numbers 19:11: "One who touches a corpse of the soul of any man."
Similarly, an olive-sized measure from the flesh of a corpse imparts impurity like an entire corpse, whether it still retains its moisture or it has become dry like a shard. Netzal is like flesh and imparts impurity when an olive-sized portion is present.
What is meant by the term netzal? Flesh that has decomposed and turned into a putrid liquid mass, provided that the liquid mass that resulted from the corpse coagulates. For if it coagulates, it is apparent that it comes from the flesh of the corpse. If it does not coagulate, it does not impart impurity, for perhaps it is from the deceased's phlegm or other body fluids.

הלכה ב
אַף עַל פִּי שֶׁהַשִּׁעוּרִין כֻּלָּם הֲלָכָה לְמשֶׁה מִסִּינַי הֵן אָמְרוּ חֲכָמִים תְּחִלַּת בְּרִיָּתוֹ שֶׁל אָדָם כְּזַיִת וּלְפִיכָךְ שִׁעוּר טֻמְאַת בְּשָׂרוֹ כְּזַיִת:
כסף משנה
2.
Even though these measures were all conveyed as halachot to Moses at Sinai, our Sages said: At the onset of his conception, man's body is the size of an olive. Therefore the measure for which his flesh imparts ritual impurity is the size of an olive.

הלכה ג
אֵיבָר שֶׁנֶּחְתַּךְ מִן הָאָדָם הַחַי הֲרֵי הוּא כְּמֵת שָׁלֵם מְטַמֵּא בְּמַגָּע וּבְמַשָּׂא וּבְאֹהֶל אֲפִלּוּ אֵיבָר קָטָן שֶׁל קָטָן בֶּן יוֹמוֹ שֶׁהָאֵיבָרִים אֵין לָהֶם שִׁעוּר שֶׁנֶּאֱמַר (במדבר יט טז) "כּל אֲשֶׁר יִגַּע עַל פְּנֵי הַשָּׂדֶה בַּחֲלַל חֶרֶב" וְהַדָּבָר יָדוּעַ שֶׁדִּין חֲלַל חֶרֶב כְּדִין חֲלַל אֶבֶן אוֹ חֲלַל שְׁאָר דְּבָרִים מִפִּי הַשְּׁמוּעָה לָמְדוּ שֶׁלֹּא בָּא זֶה אֶלָּא לְטַמֵּא נוֹגֵעַ בְּאֵיבָר שֶׁפְּלָטַתּוּ הַחֶרֶב. בַּמֶּה דְּבָרִים אֲמוּרִים כְּשֶׁהָיָה הָאֵיבָר שָׁלֵם כִּבְרִיָּתוֹ בָּשָׂר וְגִידִים וַעֲצָמוֹת שֶׁנֶּאֱמַר (במדבר יט טז) "אוֹ בְעֶצֶם אָדָם" עֶצֶם שֶׁהוּא כְּאָדָם מַה אָדָם בָּשָׂר וְגִידִים וַעֲצָמוֹת אַף אֵיבָר מִן הַחַי עַד שֶׁיִּהְיֶה כִּבְרִיָּתוֹ בָּשָׂר וְגִידִים וַעֲצָמוֹת. אֲבָל הַכֻּלְיָא וְהַלָּשׁוֹן וְכַיּוֹצֵא בָּהֶן אַף עַל פִּי שֶׁהֵן אֵיבָר בִּפְנֵי עַצְמָן הוֹאִיל וְאֵין בָּהֶן עֶצֶם הֲרֵי הֵן כִּשְׁאָר הַבָּשָׂר. חָסַר מִן הָעֶצֶם שֶׁל אֵיבָר כָּל שֶׁהוּא הֲרֵי הָאֵיבָר כֻּלּוֹ טָהוֹר. חָסַר מִבְּשָׂרוֹ אִם נִשְׁאַר עָלָיו בָּשָׂר שֶׁרָאוּי לַעֲלוֹת בּוֹ אֲרוּכָה בְּחַי וְיִתְרַפֵּא וְיִשָּׁלֵם. הֲרֵי זֶה מְטַמֵּא בְּמַגָּע וּבְמַשָּׂא וּבְאֹהֶל. וְאִם לָאו מְטַמֵּא בְּמַגָּע וּבְמַשָּׂא וְאֵינוֹ מְטַמֵּא בְּאֹהֶל. וּבָשָׂר הַפּוֹרֵשׁ מִן הַחַי טָהוֹר. וְכֵן עֶצֶם בְּלֹא בָּשָׂר הַפּוֹרֵשׁ מִן הַחַי טָהוֹר:
כסף משנה
3.
A limb that was cut off from a living person is considered as an entire corpse and imparts impurity when it is touched, carried, or one is under the same structure. This applies even to a limb of a newborn infant, for there is no minimum measure that applies with regard to complete limbs. This is derived from Numbers 19:16 which states: "Anyone who touches a corpse slain by the sword... on the open field." It is a known matter that the laws applying to one slain by the sword are the same as one slain by a stone or through other means. According to the Oral Tradition, we learned that the verse comes only to deem a limb severed by a sword as impure.
When does the above apply? When the limb was intact as it was when it came into being with flesh, sinews, and bones, as the abovementioned verse states: "Or the bone of a man." Implied is that the bone must be like a man, i.e., a human corpse. Just as a human corpse has flesh, sinews, and bones, so too, a limb from a living person must be intact as it was when it came into being and have flesh, sinews, and bones. In contrast, a kidney and a tongue, and the like, even though they are considered as complete organs, since they do not contain bones, they are considered as the remainder of a person's flesh.
If even the slightest amount of bone was missing from a limb severed from a living person, the entire limb is pure. The following rules apply if some of its flesh was missing: If there remained enough flesh on it that, were the person to be alive, his flesh would regenerate, be healed, and return to a state of wholeness, the limb imparts impurity when it is touched, carried, or when one is under the same structure. If not, it imparts impurity when it is touched, carried, but not when one is under the same structure.
Flesh that is separated from a living person is ritually pure. Similarly, a bone without flesh that is separated from a living person is ritually pure.

הלכה ד
אֵיבָר הַפּוֹרֵשׁ מִן הַמֵּת מְטַמֵּא בְּמַגָּע וּבְמַשָּׂא וּבְאֹהֶל כְּמֵת וְהוּא שֶׁיִּהְיֶה שָׁלֵם כִּבְרִיָּתוֹ בָּשָׂר וְגִידִים וַעֲצָמוֹת. חָסַר עַצְמוֹ אִם נִשְׁאַר עָלָיו בָּשָׂר כְּזַיִת מְטַמֵּא כְּמֵת שָׁלֵם. חָסַר הַבָּשָׂר וְלֹא חָסַר הָעֶצֶם אִם נִשְׁאַר עָלָיו כְּדֵי לַעֲלוֹת אֲרוּכָה בְּחַי מְטַמֵּא כְּמֵת שָׁלֵם וְאִם לָאו הֲרֵי הוּא כִּשְׁאָר עַצְמוֹת הַמֵּתִים שֶׁאֵין עֲלֵיהֶן הַבָּשָׂר:
כסף משנה
4.
When a limb is separated from a corpse, it imparts impurity as a corpse does when it is touched, carried, or when one is under the same structure, provided it is intact as it was when it came into being with flesh, sinews, and bones.
If a portion of the bone was lacking, when there is at least an olive-sized portion of flesh on it, it imparts impurity like an entire corpse. The following rules apply if some of the flesh was lacking, but none of the bone. If there remained enough flesh on it that, were the person to be alive, his flesh would regenerate, it imparts impurity like an entire corpse. If not, it is like other bones of a corpse on which there is no flesh.

הלכה ה
מֹחַ שֶׁבְּתוֹךְ הָעֶצֶם הֲרֵי הוּא מַעֲלֶה אֲרוּכָה מִבַּחוּץ. לְפִיכָךְ קוּלִית הַמֵּת וְהוּא עֶצֶם הַסָּתוּם מִשְּׁנֵי קְצוֹתָיו אִם יֵשׁ בְּתוֹכָהּ מֹחַ כְּדֵי לַעֲלוֹת אֲרוּכָה הֲרֵי זֶה כְּמֵת שָׁלֵם. הָיָה בָּהּ מֹחַ הַמִּתְנַדְנֵד אִם יֵשׁ בּוֹ כְּזַיִת הֲרֵי זֶה מְטַמֵּא בְּאֹהֶל אַף עַל פִּי שֶׁהָעֶצֶם סָתוּם מִכָּל צְדָדָיו טֻמְאָה בּוֹקַעַת וְעוֹלָה בּוֹקַעַת וְיוֹרֶדֶת כְּמוֹ שֶׁיִּתְבָּאֵר שֶׁהַמֹּחַ כְּבָשָׂר לְכָל דָּבָר:
כסף משנה
5.
The marrow of a bone causes flesh to regenerate on the bone's surface. Therefore if the hipbone of a corpse, a bone that is closed on both of its sides, has sufficient marrow to cause the flesh to regenerate, it is considered as an entire corpse.
The following laws apply if a bone has marrow that has dried out and rattles within. If there is an olive-sized portion of marrow, the bone imparts impurity when one is under the same shelter. Even though the bone is closed on all sides, the impurity breaks through and ascends and breaks through and descends, as will be explained. For the marrow is considered like flesh in all contexts.

הלכה ו
הָאֵיבָר וְהַבָּשָׂר הַמְדֻלְדָּלִים בָּאָדָם אַף עַל פִּי שֶׁאֵין יְכוֹלִין לַחְזֹר וְלִחְיוֹת טְהוֹרִים. מֵת הָאָדָם הֲרֵי הַבָּשָׂר טָהוֹר וְהָאֵיבָר מְטַמֵּא מִשּׁוּם אֵיבָר מִן הַחַי וְאֵינוֹ מְטַמֵּא מִשּׁוּם אֵיבָר מִן הַמֵּת. מַה בֵּין אֵיבָר מִן הַחַי לְאֵיבָר מִן הַמֵּת. אֵיבָר מִן הַחַי בָּשָׂר הַפּוֹרֵשׁ מִמֶּנּוּ וְעֶצֶם הַפּוֹרֵשׁ מִמֶּנּוּ טְהוֹרִים וְאֵיבָר מִן הַמֵּת בָּשָׂר הַפּוֹרֵשׁ מִמֶּנּוּ וְעֶצֶם הַפּוֹרֵשׁ מִמֶּנּוּ כִּמְפֹרָשִׁים מִן הַמֵּת הַשָּׁלֵם וּמְטַמְּאִין בְּשִׁעוּרָן:
כסף משנה
6.
The following laws apply when there is a limb and/or flesh limply hanging from a person. Even though they cannot be restored to their natural state and vitality, they are pure. If the person dies, the flesh is pure and the limb imparts ritual impurity according to the laws pertaining to a limb severed from a living body and not according to the laws pertaining to a limb severed from a corpse.
What are the differences between the laws pertaining to a limb severed from a living body and the laws pertaining to a limb severed from a corpse? Flesh and bones that become separated from a limb severed from a living person are pure. Flesh and bones that become separated from a limb severed from a corpse are considered as if they were separate from an entire corpse and impart impurity according to the appropriate measures.

הלכה ז
וּבֵין אֵיבָר מִן הַחַי בֵּין אֵיבָר מִן הַמֵּת אֵין לָהֶן שִׁעוּר. אָמְרוּ חֲכָמִים מָאתַיִם שְׁמוֹנָה וְאַרְבָּעִים אֵיבָרִים יֵשׁ בָּאִישׁ כָּל אֶחָד וְאֶחָד מֵהֶן בָּשָׂר וְגִידִים וְעֶצֶם וְאֵין הַשִּׁנַּיִם מִן הַמִּנְיָן. וּבְאִשָּׁה מָאתַיִם וְאֶחָד וַחֲמִשִּׁים. כָּל אֵיבָר מֵהֶן שֶׁפֵּרֵשׁ כִּבְרִיָּתוֹ בֵּין מִן הַחַי בֵּין מִן הַמֵּת מְטַמֵּא בְּמַגָּע וּבְמַשָּׂא וּבְאֹהֶל חוּץ מִשְּׁלֹשָׁה אֵיבָרִים יְתֵרוֹת שֶׁבָּאִשָּׁה שֶׁאֵינָן מְטַמְּאִין בְּאֹהֶל. וְכֵן אֶצְבַּע יְתֵרָה שֶׁיֵּשׁ בָּהּ עֶצֶם וְאֵין בָּהּ צִפֹּרֶן אִם נִסְפֶּרֶת עַל גַּב הַיָּד עוֹלָה לְמִנְיַן רֹב הָאֵיבָרִים וְאִם אֵינָהּ נִסְפֶּרֶת עַל גַּב הַיָּד מְטַמְּאָה בְּמַגָּע וּבְמַשָּׂא וְאֵינָהּ מְטַמְּאָה בְּאֹהֶל וְטֻמְאָתָהּ מִדִּבְרֵי סוֹפְרִים. וְאִם הָיָה בָּהּ צִפֹּרֶן הֲרֵי הִיא כִּשְׁאָר הָאֵיבָרִים. וּמִפְּנֵי מָה גָּזְרוּ טֻמְאָה עַל אֶצְבַּע שֶׁאֵינָהּ נִסְפֶּרֶת גְּזֵרָה מִשּׁוּם הַנִּסְפֶּרֶת. וְלָמָּה לֹא טִמְּאוּהָ בְּאֹהֶל עָשׂוּ לָהּ הֶכֵּר כְּדֵי לְהוֹדִיעַ שֶׁטֻּמְאָתָהּ מִדִּבְרֵיהֶם מִשּׁוּם גְּזֵרָה כְּדֵי שֶׁלֹּא יִשְׂרְפוּ עַל טֻמְאָתָהּ תְּרוּמָה וְקָדָשִׁים:
כסף משנה
7.
There is no minimum measure for either a limb severed from a living body or a limb severed from a corpse.
A man has 248 limbs, every one of them comprising flesh, sinews, and bones. The teeth are not included in this number. There are 251 in a woman.
Any limb that became separated while intact as it was when it came into being, whether it was separated while the person was alive or after his death imparts impurity when it is touched, carried, or one is under the same structure with the exception of the three extra limbs possessed by a woman. The latter do not convey impurity when one is under the same structure.
Similarly, an extra finger that has a bone, but does not have a nail, can be counted as part of the sum of the majority of a person's limbs if it is counted on his hand together with his other fingers. If it is not counted on his hand together with his other fingers, it can, nevertheless, impart impurity when it is touched or carried. It does not, however, impart impurity when one is under the same shelter. The impurity it imparts is of Rabbinic origin. If it has a nail, it is considered as other limbs.
Why did the Sages rule that a finger that is not counted should impart impurity? This decree was a safeguard lest the impurity that could be imparted by one that is counted would be ignored. Why did they rule that it does not impart impurity when under the same shelter? They established a point of distinction to make it known that the impurity it imparts originates in a Rabbinic decree so that terumah and sacrificial meat will not be burnt because of this type of impurity.

הלכה ח
עַצְמוֹת הַמֵּת שֶׁאֵין עֲלֵיהֶם בָּשָׂר אִם נִכֶּרֶת בָּהֶן צוּרַת עֲצָמוֹת הֲרֵי אֵלּוּ מְטַמְּאִין בְּמַגָּע וּבְמַשָּׂא וּבְאֹהֶל כְּמֵת שָׁלֵם שֶׁאֲנִי קוֹרֵא בָּהֶם (במדבר יט טז) "עֶצֶם אָדָם". וְאֵלּוּ הֵן הָעֲצָמוֹת שֶׁהֵן מְטַמְּאִין כְּמֵת. הַשִּׁדְרָה וְהַגֻּלְגּלֶת וְרֹב בִּנְיָנוֹ וְרֹב מִנְיָנוֹ. הַשִּׁדְרָה כֵּיצַד. שִׁדְרָה שֶׁהִיא שְׁלֵמָה הֲרֵי הִיא כְּמֵת שָׁלֵם וְאִם חָסְרָה אֲפִלּוּ חֻלְיָא אַחַת מִשְּׁמוֹנֶה עֶשְׂרֵה חֻלְיוֹת הֲרֵי הִיא כִּשְׁאָר הָעֲצָמוֹת. הַגֻּלְגּלֶת כֵּיצַד. גֻּלְגּלֶת שֶׁהִיא שְׁלֵמָה הֲרֵי הִיא כְּמֵת וְאִם חָסְרָה כְּסֶלַע הֲרֵי הִיא כִּשְׁאָר הָעֲצָמוֹת. הָיוּ בָּהּ נְקָבִים קְטַנִּים כֻּלָּם מִצְטָרְפִין לִכְסֶלַע. כָּל בִּנְיָנוֹ שֶׁל אָדָם הוּא שְׁתֵּי הַשּׁוֹקַיִם וְהַיְרֵכַיִם וְהַצְּלָעוֹת וְהַשִּׁדְרָה. וְרֹב בִּנְיָנוֹ שֶׁל מֵת הֲרֵי הוּא כְּמֵת שָׁלֵם. כֵּיצַד. כְּגוֹן שְׁתֵּי שׁוֹקָיו וְיָרֵךְ אַחַת אִם חָסֵר רֹב בִּנְיָנוֹ כָּל שֶׁהוּא הֲרֵי הֵן כִּשְׁאָר הָעֲצָמוֹת. רֹב מִנְיָנוֹ כֵּיצַד. רֹב מִנְיַן עֲצָמוֹת כְּגוֹן שֶׁהָיוּ קכ''ה עֶצֶם הֲרֵי אֵלּוּ כְּמֵת שָׁלֵם. הָיוּ קכ''ד הֲרֵי הֵן כִּשְׁאָר הָעֲצָמוֹת. אַף עַל פִּי שֶׁהָיָה אָדָם זֶה יָתֵר בְּאֵיבָרָיו אוֹ חָסֵר בְּאֵיבָרָיו אֵין מַשְׁגִּיחִין בּוֹ אֶלָּא עַל מִנְיַן רֹב כָּל אָדָם אֶלָּא אִם כֵּן הָיְתָה אֶצְבַּע שֶׁיֵּשׁ בָּהּ צִפֹּרֶן אוֹ שֶׁהָיְתָה נִסְפֶּרֶת עַל גַּב הַיָּד שֶׁהִיא עוֹלָה לְמִנְיָן כְּמוֹ שֶׁבֵּאַרְנוּ:
כסף משנה
8.
If there is no flesh on the bones of a corpse, they impart impurity like an entire corpse when they are touched or carried or when one is under the same structure, provided it is apparent that they have the form of bones, for one can still refer to them as "the bones of a man." These are the bones that impart the ritual impurity of a corpse: the backbone, the skull, the majority of the body's structure, and the majority of the number of bones in the body.
What is meant by the backbone causing impurity? When the backbone is intact, it is considered as an entire corpse. If even one of the eighteen vertebrae is missing, they are considered as other bones.
What is meant by the skull causing impurity? When the skull is intact, it is considered as an entire corpse. If it is missing a portion as large as a sela, it is considered as other bones. If it has small holes, their area is added together to see if it compromises that of a sela.
The entire structure of a man is: the two shins, the hips, the ribs, and the backbone. The majority of the structure of a corpse is considered as an entire corpse. What is implied? For example, if his two shins and one hip are present, it is as if the entire corpse was present. If even the slightest amount is missing from "the majority of the structure," the bones are considered as other bones.
What is meant by the majority of the number of the bones? The majority of the number of bones, e.g., 125 bones. If there are 124, they are considered as other bones. Even though this particular person had extra limbs or fewer limbs, this figure is calculated according to the number of bones of the majority of people unless the extra limb is a finger that has a nail or which is counted on his hand together with his other fingers. Such a finger is counted in the sum of a person's bones, as stated.

הלכה ט
שְׁאָר עַצְמוֹת הַמֵּת שֶׁאֵין בָּהֶן רֹב מִנְיַן וְלֹא רֹב בִּנְיָן וְלֹא שִׁדְרָה שְׁלֵמָה וְלֹא גֻּלְגּלֶת שְׁלֵמָה אִם הָיָה בָּהֶן רֹבַע הַקַּב הֲרֵי אֵלּוּ מְטַמְּאִים כְּמֵת בְּמַגָּע וּבְמַשָּׂא וּבְאֹהֶל. הָיוּ פָּחוֹת מֵרֹבַע אֲפִלּוּ עֶצֶם כִּשְׂעוֹרָה מְטַמֵּא בְּמַגָּע וּבְמַשָּׂא וְאֵינוֹ מְטַמֵּא בְּאֹהֶל:
כסף משנה
9.
The following laws apply to the remaining bones of a corpse when among them, there is not the majority of the number, nor the majority of the structure of the corpse, and not an intact backbone, nor an intact skull. If there are a fourth of a kab of bones, they impart impurity like an entire corpse when they are touched or carried or one is under the same structure. If there are less than a fourth of a kab - this applies even to a bone merely the size of a barley-corn - they impart impurity when they are touched or carried. They do not, however, impart impurity through being under the same structure.

הלכה י
הָיָה עֶצֶם אֶחָד אֲפִלּוּ יֵשׁ בּוֹ רֹבַע הֲרֵי זֶה מְטַמֵּא בְּמַגָּע וּבְמַשָּׂא וְאֵינוֹ מְטַמֵּא בְּאֹהֶל. טֻמְאַת עֶצֶם אֶחָד הֲלָכָה מִפִּי הַשְּׁמוּעָה לְפִי שֶׁנֶּאֱמַר (במדבר יט יח) "כָּל הַנּוֹגֵעַ בַּעֶצֶם" לָמְדוּ מִפִּי הַשְּׁמוּעָה אֲפִלּוּ עֶצֶם כִּשְׂעוֹרָה מְטַמֵּא בְּמַגָּע וּבְמַשָּׂא. וּלְפִי שֶׁטֻּמְאָתוֹ הֲלָכָה הֲרֵי הוּא דִּין תּוֹרָה וְלֹא מִדִּבְרֵי סוֹפְרִים:
כסף משנה
10.
If there is one bone, even if it is a fourth of a kab in size, it imparts impurity when it is touched or carried. It does not, however, impart impurity through being under the same structure.
The impurity imparted by one bone is a halachah conveyed by the Oral Tradition. Numbers 19:18 states: "And all who touch the bone." The Oral Tradition teaches that even a bone the size of a barley-corn imparts impurity when it is touched or carried. Since this impurity is taught as halachah by the Oral Tradition, it is considered as Scriptural Law and not as a Rabbinic decree.

הלכה יא
מֵת שֶׁהִרְקִיבוּ עַצְמוֹתָיו בַּקֶּבֶר וְנַעֲשׂוּ רֶקֶב. מְלֹא חָפְנַיִם מֵאוֹתוֹ רֶקֶב מְטַמֵּא בְּמַשָּׂא וּבְאֹהֶל כְּמֵת וְאֵינוֹ מְטַמֵּא בְּמַגָּע לְפִי שֶׁאִי אֶפְשָׁר לִגַּע בְּכֻלּוֹ שֶׁהֲרֵי אֵינוֹ גּוּף אֶחָד. וַאֲפִלּוּ גִּבְּלוֹ בְּמַיִם אֵינוֹ חִבּוּר:
כסף משנה
11.
When the bones of a corpse decompose in the grave and become a rekev, two handfuls of that rekev impart impurity when that quantity is carried or it is located under the same structure as a person or object. It does not, however, impart impurity when it is touched, because it is impossible to touch it in its entirety, because it is not a whole entity. Even if it was mixed with water, the different portions are not considered as joined together.

הלכה יב
דַּם הַמֵּת מְטַמֵּא כְּמֵת בְּמַגָּע וּבְמַשָּׂא וּבְאֹהֶל. שֶׁנֶּאֱמַר (במדבר יט יג) "בְּנֶפֶשׁ הָאָדָם" וְנֶאֱמַר (דברים יב כג) "כִּי הַדָּם הוּא הַנָּפֶשׁ". וְכַמָּה שִׁעוּרוֹ רְבִיעִית. אֲפִלּוּ תַּמְצִית הַדָּם כָּל זְמַן שֶׁיֵּשׁ בּוֹ אַדְמוּמִית מְטַמֵּא בְּאֹהֶל הַמֵּת:
כסף משנה
12.
The blood of a corpse imparts impurity like the corpse itself when it is touched, carried, or one is under the same structure, for Numbers 19:13 speaks of: "the soul of man" and Deuteronomy 12:23 states: "the blood is the soul."
What is the measure of blood that imparts impurity? A revi'it. Even the liquid left after blood coagulates imparts impurity when one is under the same structure, as a corpse does, as long as it is red in color.

הלכה יג
דַּם הַחַי אֲפִלּוּ דַּם נְחִירָה הֲרֵי זֶה טָהוֹר כָּל זְמַן שֶׁהוּא חַי. נִתְעָרֵב הַדָּם שֶׁיָּצָא מִמֶּנּוּ בָּאַחֲרוֹנָה סָמוּךְ לַמִּיתָה עִם הַדָּם שֶׁיָּצָא מִמֶּנּוּ אַחַר שֶׁמֵּת וְכָל הַתַּעֲרוֹבוֹת רְבִיעִית וְאֵין יָדוּעַ כַּמָּה יָצָא מֵחַיִּים וְכַמָּה יָצָא אַחַר מִיתָה. אֲפִלּוּ חֲצִי רְבִיעִית מֵחַיִּים וְחֶצְיָהּ אַחַר מִיתָה הֲרֵי זֶה נִקְרָא דַּם תְּבוּסָה וּמְטַמֵּא בְּמַשָּׂא וּבְמַגָּע וּבְאֹהֶל. אֶלָּא שֶׁטֻּמְאָתוֹ מִדִּבְרֵי סוֹפְרִים:
כסף משנה
13.
Blood from a living person, even if it is the blood that flows out when the person is stabbed in the throat, is pure as long as the person is alive. If the blood which flows from his body at the end, i.e., before his death, becomes mixed with the blood which flows from his body after he died and the entire mixture is a revi'it, and it is not known how much flowed out while he was alive and how much flowed out after his death, even if half a revi'it flowed out while he was alive and half after his death, this is referred to as "weltering blood." It imparts impurity when it is touched, carried, or when one is under the same structure. This impurity is, however, of Rabbinic origin.

הלכה יד
הָרוּג שֶׁהָיָה מֻטָּל עַל הַמִּטָּה וְדָמוֹ מְנַטֵּף כְּשֶׁהוּא חַי וְיוֹרֵד לְגֻמָּא וּמֵת וַהֲרֵי הַדָּם מְנַטֵּף אַחַר מוֹתוֹ וְיוֹרֵד לְאוֹתָהּ גֻּמָּא. הֲרֵי כָּל הַדָּם שֶׁבָּהּ טָהוֹר שֶׁטִּפָּה טִפָּה רִאשׁוֹנָה רִאשׁוֹנָה בָּטְלָה כְּדָם שֶׁיָּצָא מֵחַיִּים. יָצָא מִמֶּנּוּ רְבִיעִית דָּם בִּלְבַד וְסָפֵק כֻּלָּהּ מֵחַיִּים סָפֵק כֻּלָּהּ לְאַחַר מִיתָה הֲרֵי זוֹ סְפֵק טְמֵאָה כִּשְׁאָר הַסְּפֵקוֹת וְהַנּוֹגֵעַ בָּהּ בִּרְשׁוּת הַיָּחִיד טָמֵא בִּרְשׁוּת הָרַבִּים טָהוֹר כְּמוֹ שֶׁיִּתְבָּאֵר בִּמְקוֹמוֹ:
כסף משנה
14.
The following laws apply when the corpse of a person who was slain was lying on a bed. His blood had been dripping from his body while he was alive and descending into a hole. At one point, he died. After he died, the blood continued dripping and descending into that hole. All of the blood is pure. For the drops of blood are nullified one by one, as they become mixed with the blood that flowed from his body during his lifetime.
If only a revi'it of blood flowed out from the person's body and there is a doubt whether it all flowed out during the person's life or afterwards, this is a questionable situation of ritual impurity like other questionable situations. One who touches it in a private domain is impure. In a public domain, he is pure, as will be explained in the appropriate place.

הלכה טו
הַקֶּבֶר כָּל זְמַן שֶׁהַטֻּמְאָה בְּתוֹכוֹ מְטַמֵּא בְּמַגָּע וּבְאֹהֶל כְּמֵת דִּין תּוֹרָה. שֶׁנֶּאֱמַר (במדבר יט טז) "אוֹ בְמֵת אוֹ בְעֶצֶם אָדָם אוֹ בְקָבֶר". וְאֶחָד הַנּוֹגֵעַ בְּגַגּוֹ שֶׁל קֶבֶר אוֹ הַנּוֹגֵעַ בִּכְתָלָיו. וְהוּא שֶׁיִּהְיֶה בָּנוּי וְסָתוּם וְאַחַר כָּךְ יִהְיֶה כֻּלּוֹ מְטַמֵּא בְּמַגָּע וּבְאֹהֶל. אֲבָל הַמַּעֲמִיד כֵּלִים אוֹ אֲבָנִים וְכַיּוֹצֵא בָּהֶן בְּצִדֵּי הַמֵּת וְכִסָּה עָלָיו מִלְּמַעְלָה בְּכֵלִים אוֹ בַּאֲבָנִים וְכַיּוֹצֵא בָּהֶן זֶה הַכִּסּוּי הַמֻּטָּל מִלְּמַעְלָה נִקְרָא גּוֹלֵל וְאֵלּוּ הַצְּדָדִין הַמַּעֲמִידִין אֶת הַגּוֹלֵל שֶׁהוּא נִשְׁעָן עֲלֵיהֶן נִקְרָאִין דּוֹפֵק. וּשְׁנֵיהֶם הַגּוֹלֵל אוֹ הַדּוֹפֵק מְטַמְּאִין בְּמַגָּע וּבְאֹהֶל כְּקֶבֶר וְטֻמְאָתָן מִדִּבְרֵי סוֹפְרִים וְאֵינָן מְטַמְּאִין בְּמַשָּׂא. לְפִיכָךְ אִם גָּרַר הַגּוֹלֵל בַּחֲבָלִים עַד שֶׁכִּסָּה בּוֹ אֶת הַמֵּת. אוֹ גְּרָרוֹ אוֹ שְׁמָטוֹ מֵעַל הַמֵּת. אוֹ שֶׁגָּרַר הַדּוֹפֵק עַד שֶׁהֶעֱמִיד עָלָיו הַגּוֹלֵל אוֹ שְׁמָטוֹ בַּחֲבָלִים מִתַּחַת הַגּוֹלֵל הֲרֵי זֶה טָהוֹר. וּדְבָרִים שֶׁסּוֹמְכִין אֶת הַדּוֹפֵק וְהֵם הַנִּקְרָאִין דּוֹפֵק דּוֹפְקִין הֲרֵי הֵן טְהוֹרִין:
כסף משנה
15.
According to Scriptural Law, as long as the source of impurity is in a grave, the grave imparts impurity when it is touched or when one is under the same structure, as a corpse does, for Numbers 19:16 mentions touching "a corpse, the bone of a man, or a grave." A person is impure whether he touches the covering of a grave or its sides, provided it is built and totally enclosed. Afterwards, in such a situation, the grave imparts impurity in its entirety when it is touched or when one is under the same structure.
If, however, one places keilim, stones, or the like at the side of a corpse and covers the corpse with keilim, stones, or the like, the covering that shelters the corpse from above is called a gollel. And the objects at the side that support the gollel and upon which it rests are called a dofek. Both of them, the gollel and the dofek impart impurity when they are touched or when one is under the same structure, as is true with regard to a grave. The impurity they impart is of Rabbinic origin. They do not impart impurity when carried. Accordingly, if one drags a gollel with ropes until it covers a corpse or drags it or pulls it away from being above a corpse, or one dragged a dofek until he positioned the gollel above it or pulled it by ropes from under the dofek, the person is pure.
Entities that support the dofek are called dofek dofekkim and they are pure.

הלכה טז
שָׂדֶה שֶׁנֶּחְרַשׁ בָּהּ קֶבֶר וְאָבְדוּ עַצְמוֹת הַמֵּת בַּעֲפָרָהּ הִיא הַנִּקְרֵאת בֵּית הַפְּרָס. וַעֲפָרָהּ מְטַמֵּא בְּמַגָּע וּבְמַשָּׂא שֶׁמָּא יֵשׁ בָּהּ עֶצֶם כִּשְׂעוֹרָה. וְאֵינָהּ מְטַמְּאָה בְּאֹהֶל. וְכֵן כָּל אַרְצוֹת הָעַכּוּ''ם עֲפָרָן מְטַמֵּא בְּמַגָּע וּבְמַשָּׂא מִפְּנֵי הָעֲצָמוֹת שֶׁאֵין נִזְהָרִין בָּהֶן. וְטֻמְאַת בֵּית הַפְּרָס וְאֶרֶץ הָעַכּוּ''ם מִדִּבְרֵי סוֹפְרִים כְּמוֹ שֶׁיִּתְבָּאֵר:
כסף משנה
16.
When a field containing a grave was plowed and the bones of the corpse were lost in its earth, this is called a beit hapras. Its earth imparts impurity when it is touched or carried, for perhaps it contains a bone the size of a barley corn, but it does not impart impurity when one is under the same structure.
Similarly, the earth in the entire Diaspora imparts impurity when it is touched or carried, because of the possibility of the presence of bones, for they are not careful about burying them. The impurity of a beit hapras and the earth of the Diaspora is of Rabbinic origin, as will be explained.

טהרה הלכות טומאת מת פרק ב
Taharah Tumas Meis Chapter 2