I don't know the Lasance missal, but in the most widespread hand missal in Germany, Graduale and Alleluja/Graduale and Tractus/Alleluja and Alleluja are always typeset as a single paragraph.
Hand Missals usually take their text from the Missale Romanum, not the Graduale. Now in the Missale Romanum the text would be read by the priest as one text, so most hand Missals would also do the same, although the St. Andrew Missal does have them separate in some places but not others. Note the text in the Graduale is not always the same as that in the Missale Romanum!
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