398. According to the computation of Prof. Hartel there are 3354 places in which the effect of the digamma can be traced on the meter of Homer. In 2324 places its presence is shown by hiatus after a short vowel (i. e. it prevents elision); in 359 places it justifies the lengthening of a short syllable ending in a consonant, in other words, it helps to make positiοn; in 164 places it follows a long vowel or diphthong which is without ictus; in 507 places it follows a long vowel or diphthong with ictus. It is further to be noticed that in many places a short final vowel in arsis is lengthened before the ϝ: see especially the instances given under ἕο (§ 390), and ἀχωω (§ 389).[fn]A short vowel is also lengthened vwith ictus before ἔπος (Od. 10.246), ἔρξαν (Od. 14.411), and in the compounds ἀπο-ειπών (Il. 19.35) and ἀπο-έρσῃ, ἀπο-έρσειε (Il. 21.283 & 329)[/fn] On the other hand there are 617 places where the ϝ is neglected. Short vowels suffer elision before it in 324 places, it fails to lengthen by position after another consonant in 215 places, and long vowels or diphthongs are shortened before it in 78 places. Also the power to lengthen by position is confined, except in the case of the enclitic ἑο, οἱ, to lengthening of syllables which have the ictus.