Reference for Yevamot 150:16

ההוא עובדא דהוה במתא מחסיא שפייה מר בר רב אשי כקולמוס ואכשריה ההוא עובדא דהוה בפומבדיתא איסתתים גובתא דשכבת זרע ואפיק במקום קטנים סבר רב ביבי בר אביי לאכשורי אמר רב פפי משום דאתו

In a case where a puncture beginning below the corona terminated<span class="x" onmousemove="('comment',' By sloping upwards towards the body. ');">²¹</span> at the other end of it above the corona, R. Hiyya b. Abba desired to declare the sufferer as fit.<span class="x" onmousemove="('comment',' Since one end of the perforation is below the corona. ');">²²</span> Said R. Assi to him: Thus ruled R. Joshua b. Levi, '[A perforation of] any size in the corona constitutes a bar [against fitness]'. IF, HOWEVER, ANY PART OF THE CORONA REMAINED etc. Rabina, while sitting [at his studies], raised the following question: Must the HAIR'S BREADTH of which they spoke extend over the entire circumference thereof or only over its greater part? — 'The HAIR'S BREADTH', said Rabbah<span class="x" onmousemove="('comment',' So Emden. Cur. edd. 'Raba'. ');">²³</span> Tosfa'ah to Rabina, must extend over the greater part of it and towards its upper section'.<span class="x" onmousemove="('comment',' Which is nearer to the body. ');">²⁴</span> R. Huna ruled: If it<span class="x" onmousemove="('comment',' The corona. ');">²⁵</span> is cut away like a reed pen it constitutes no disqualification; if like a gutter<span class="x" onmousemove="('comment',' The cut running across the centre and leaving the sides intact. ');">²⁶</span> it causes disqualification. For in the latter case the air penetrates;<span class="x" onmousemove="('comment',' Cooling the membrum and preventing the flow of the semen. ');">²⁷</span> in the former it does not. R. Hisda, however, ruled: [If the cut was] in the shape of a gutter no disqualification is constituted; if it had the shape of a reed pen disqualification is constituted. For in the first case friction may be produced; in the latter it cannot. Raba said: It is reasonable to adopt the view of R. Huna that in the latter case the air penetrates while in the former it does not. For in regard to friction it is only like a bung in a cask.<span class="x" onmousemove="('comment',' Though the bung is cut away at its lower end it nevertheless closes the hole with its upper part which comes in contact with the sides of the bung hole. The contact produced by the upper part of the membrum is sufficient for the generation of the heat required for fertilization. ');">²⁸</span> Said Rabina to Meremar: Thus said Mar Zutra in the name of R. Papa, 'The law is that no disqualification is constituted whether the corona was cut away like a reed pen or like a gutter He raised, however, the question. [whether such a cut must be] below the corona or may even be above it?<span class="x" onmousemove="('comment',' Which is nearer to the body. ');">²⁴</span> — It is obvious that it may even be above it; for were it to be below the corona, the man would be regarded as fit even if the entire membrum there had been cut off. Rabina, however,<span class="x" onmousemove="('comment',' In raising a question the answer to which was so obvious. ');">²⁹</span> only desired to test Meremar. Such an incident<span class="x" onmousemove="('comment',' The cut having taken the shape of a gutter. ');">³⁰</span> once occurred at Matha Mehasia, and R. Ashi arranged for the corona to be cut into the shape of a reed pen, and then declared the man to be fit. It once happened at Pumbeditha that a man had his semen duct blocked, and the discharge of the semen made its way through the urinal duct. R. Bibi b. Abaye intended to declare the man fit. R. Papi, however, said to him, 'Because you are yourselves

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