Until about the fifth century A.D., vellum MSS. were in the roll form, but then came a change to the book form as we now know it. This change was probably due to the fact that stabbed binding, the only sort then used, was not suited to vellum. The few papyri that exist in book form were stabbed, that is to say, the rectangular pages were kept in position by a binding cord laced through holes pierced sideways right through the entire thickness of the back of the book. The marks of these holes can often be seen along the inner margins of ancient papyri, and they also show in many instances of rebound copies of our early English printed books. To-day plenty of examples of this form of sewing can be seen in the Chinese and Japanese books, “Orihons,” which are really links between the roll and the book form. It is also largely used for thin books of little value, and a modification of it can be seen in numbers of magazines, books of advertisements, and the like, which are kept together by abominable little clamps of wire attached on the same principle. When such books have to be properly bound the little clamps have to be carefully removed, and it is generally found that they have made an indelible stain of rust on the paper, even if they have not also torn it considerably. [Illustration: FIG. 23.--Stabbed binding.] In mediæval libraries or monasteries when a book was to be made, vellum leaves were cut into the required size and folded once across the middle. The folded leaves were then fitted inside each other in groups of four (quaternions) or five (quinternions), or whatever other number seemed good to the bookmaker. The leaves were then marked in some slight way so that their order might not be lost, and sent to the scribe to be written upon. The books count as folios because each original sheet only forms two pages; the fact of their being arranged in groups is accidental, and does not theoretically alter the size of the book. For this the original skin of vellum would have to be folded with certain further divisions, and in the case of early manuscripts this was never done. Vellum shows a different surface on the flesh side to that on the hair side, and the scribe usually made his rule marks with a blunt style to guide his writing on the hair side, so that on this side the ruled lines are slightly indented, whereas on the flesh side they show as little ridges. This point is apparently trivial, but if, as seems likely, both Greek and Latin scribes were really very particular and consistent in the way they alternated the two sides of the vellum, then the matter becomes one of much critical importance. Indeed, it has already been of the utmost value in deciding questions as to whether new pages had been added or not to an old book. [Illustration: FIG. 24.--Quaternion threaded together.]