Reference for Chullin 258:12

אמצעיתא נשחטה הבהמה הוכשרה בדמיה דברי ר' מאיר

or R'Johanan!<span class="x" onmousemove="('comment',' According to R. Johanan the reason for R. Simeon's view is that he holds that where by taking hold of the smaller part the greater part would not come away with it the former cannot be regarded as one with the latter (cf. supra 127b) .');">⁸</span>

Jastrow