. . "In order to maintain the stability of components in blood plasma or blood serum to be developed and retained, as described above, the development portion 12 may contain a stabilizing agent, for example, saccharides such as sucrose, trehalose, lactose, glucose, or the like, salts such as sodium chloride, potassium chloride, or the like, buffers such as glycine, a phosphate buffer, a citrate buffer," . . .