6 176 sum c gemination reply 6 176 sum c gemination syntactic afterthought gemination sorry come late discussion summary notes celtic mutation called gemination works thurneysen grammar old irish one quick call subsequent work shown mostly meant absence lenition nasalization actual twinning doubling sound vestige common celtic pre irish c nasal c boundaries opposed caused lenition v c nasalization c nasal c nasalization realized voicing unvoiced initial stops nasalization voiced stops variations ornate go note old irish various kinds subordination marked often lenition nasalization initial consonant initial word clause usu verb course see thurneysen exhaustive display facts speak mod breton impression brythonic situation largely reflects similar system