It is difficult to determine even the proximate date of these glasses. 369 From the degraded character of their art they are evidently of a comparatively late period. Garrucci and some other writers, indeed, assign them to the third or fourth century; but from the occurrence of the nimbus, and for other technical reasons, Marriott attributes many of them to the fifth or sixth century.[623] Other peculiarities of execution are characteristic of Byzantine art, and a writer in the _Revue Chrétienne_ asserts that there is not a single example of this mode of treatment known to belong to the Roman period. The striking corruption of doctrine and practice indicated is also an evidence of late origin. Numerous small cups or flasks, known as _ampullæ_, have been found affixed to the walls or imbedded in the plaster of the tombs, frequently containing in the bottom a reddish deposit. This Bosio concluded was dried blood, and therefore asserted that these cups were irrefragable proofs of the martyrdom of the persons to whose graves they were attached. The Roman ecclesiastical authorities received this theory with enthusiasm, and in the year 1688 issued a decree that, “The Holy Congregation of Relics, having carefully examined the matter, decides that the palm and vessel tinged with blood are to be considered most certain signs of martyrdom.” Eminent Romanist writers have unflinchingly asserted, without the least corroboration of their theory from contemporary evidence, that these cups were filled with the martyr’s blood and affixed to his grave;[624]--another example of the fatal mistake of Rome in fortifying truth with the bulwark of 370 falsehood, and thus shaking our confidence even in that which is real. The Acts of the Martyrs, indeed, mention the collecting of their blood in napkins, sponges, or veils, to keep as a talisman and heirloom at home; but never of its preservation in a cup, or burial beside their graves. This symbol does not occur on the tombs of some who were unquestionably martyrs;[625] and some who have it, from their extreme youth, or from some other reason indicated by the inscription, cannot have belonged to that honoured class.[626] Moreover, as Mr. Seymour remarks, some of these alleged martyr blood-cups are of a form and exhibit designs unknown till long after the age of persecution.[627] In the example on the following page, given by Aringhi, the inscription is unwarrantably translated by Romanist epigraphists, “the blood of Saturnius;” instead of, in analogy with numerous other inscriptions, “the place [_locus_] of holy Saturnius.”