| 摘要 |
Blood is transferred from a test tube having a supply of blood covered by a head of foamed blood into a second tube which is provided with a graduated scale and both ends of which are open. An apparatus for performing the transfer includes a cap having a sleeve which is frictionally attached to and surrounds one end portion of the second tube. The cap further includes a bottom wall which is spaced apart from the end face of the one end portion of the second tube, a nipple which extends from the bottom wall in a direction away from the second tube, and an elastic sealing element which surrounds the sleeve and can slide along the internal surface of the test tube toward the supply of blood therein. The nipple defines a portion of a first path wherein the resistance to the flow of blood is much less pronounced than the resistance to the flow of foam along a second path which is defined by the cap in a region adjacent to the bottom wall. This ensures that the second path permits the escape of air from the interior of the test tube into the second tube while the nipple penetrates through the head of foam and into the supply of blood below such head. The flow of a solid column of blood into the second tube along the first path takes place as soon as the intake end of the second path is immersed into the foam. The minimal cross-sectional area of the second path is less than one fourth of the minimal cross-sectional area of the first path, and neither of these paths is wide enough to permit the penetration of foam. The column of blood in the second tube can be used for determination of the speed of descent of red blood cells. Since the second tube receives only a solid column of blood, the upper end of such column can be brought into accurate register with a selected graduation on the second tube. |
