Reference for Makhshirin 4:6
קֻפָּה שֶׁהִיא מְלֵאָה תֻרְמוֹסִין וּנְתָנוּהָ לְתוֹךְ מִקְוֶה, מוֹשִׁיט יָדוֹ וְנוֹטֵל תֻּרְמוֹסִין מִתּוֹכָהּ, וְהֵם טְהוֹרִים. הֶעֱלָם מִן הַמַּיִם, הַנּוֹגְעִים בַּקֻּפָּה, טְמֵאִים, וּשְׁאָר כָּל הַתֻּרְמוֹסִים, טְהוֹרִים. צְנוֹן שֶׁבַּמְּעָרָה, נִדָּה מְדִיחָתוֹ וְהוּא טָהוֹר. הֶעֱלַתּוּ כָל שֶׁהוּא מִן הַמַּיִם, טָמֵא:
[If] a basket full of lupines was put into a <i>Mikveh</i> [ritual bath] one may reach his hand and take out the lupines from it [the basket] and they are [remain] pure [that is, not susceptible to impurity]. If he lifted them [the entire basket] from the water those that touch the basket are impure [subject to impurity] and all the rest of the lupines are pure. [If] a radish is in a cave, a <i>Niddah</i> [a woman who has menstruated and is thereby impure] may wash it and it [remains] pure. [If] she raised it out of the water at all it is impure.