Reference for Eruvin 165:1
תנא וחצי חצי חציה לטמא טומאת אוכלין ותנא דידן מ"ט לא תני טומאת אוכלין משום דלא שוו שיעורייהו להדדי
One taught: And half of the half of its half<span class="x" onmousemove="('comment',' Of the size of the loaf prescribed in our Mishnah by R. Johanan and R. Simeon respectively.');"><sup>1</sup></span> is the size susceptible to levitical uncleanness of food.<span class="x" onmousemove="('comment',' According to R. Johanan the size is three quarters of an egg. For, since he defined the size of a whole loaf as a quarter of a lab, or six eggs, the 'half of the half of its half' must be equal to 6/2 X 2 X 2 = 3/4 of an egg. According to R. Simeon, since a whole loaf is equal to 1/3 of a kab, or 24/3 = 8 eggs, the 'half of the half of its half' must be equal to 8/2 X 2 X 2 = 1 egg.');"><sup>2</sup></span> But why did not our Tanna mention<span class="x" onmousemove="('comment',' In our MISHNAH:');"><sup>3</sup></span>