Reference for Niddah 41:32

לא טימא רבי יהודה אלא בחתיכה של ארבעת מיני דמים והא קתני ירוקה ולבנה ופליג רבי יהודה

[In such a case.] R. Judah holds, one must be guided by the nature of most of shapeless objects, and most shapeless objects have the colour of one of the four kinds of blood, while the Rabbis hold that we do not say, 'most shapeless objects have the colour of one of the four kinds of blood'. But is this correct?<span class="x" onmousemove="('comment',' Lit., 'I am not'. ');">²⁷</span>

Jastrow