Missing folios

[Wladimir D]

You are mistaken. Kraus did not sew quires Q9 and Q11; consequently, the "spacers" were already present until the 20th century. The thread of Krfus, used in the initial and final quires is thin and white. Furthermore, the images show that the quality of the old threads varies: the thread in Q9 consists made of two strands (left-hand twist), whereas Q1 features a  right-hand twist, and the thread in Q11 consists of three strands braided together (braid). This suggests that these quires were sewn by different people (or at different times, using whatever materials were at hand).
I do not believe these "spacers" are remnants of trimmed leaves. I think the reason for inserting the "spacers" is as follows: in terms of weight, Q9 is comparable to ROS. It consists of 5.5 leaves, and a spacer was inserted to prevent the fold line from tearing. Q11 is also a "heavy" quire, comprising 4.5 leaves.

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