gorge. There is a curious relationship between "gorge" and "throat." OED
inverted "e" I assume Bely is referring to the "schwa" a mid-central unrounded vowel. The word "schwa" is borrowed from Hebrew. Meillet among others discusses this vowel (94). Brugmann also covers the vowel (80 ff.)
inverted "e" , or "a" in "ar," "al" turned into "ir," "ur" Bely cites Porzezinski for this development, but I have not been able to verify his findings with Meillet or Brugmann,
Wiktor Porzezinski, Ocherk sravnitel'noj fonetiki. str. 17, 18. I have been unable to obtain this work to check the accuracy of Bely's presentation. Porzezinski published in both Russian and German. He had lectured at Moscow University and Bely may have made his acquaintance through his own father, Professor Nikolai Bugaev. Bely in papers in his archive at the Russian State Library in Moscow "K zvuku slov" cites the volume as "Moscow, 1911). (See Fond 25, karton 3, ed. xr. 12).