Referring to FIG. 8A, shown is a schematic drawing illustrating a top view of the needle and barrel assembly 700, as shown in FIG. 7, with the needle concealed inside the barrel, and with an optional safety cap 189 engaged, according to the fourth embodiment of the invention; FIG. 8B illustrates a left side-view of the apparatus shown in FIG. 8A; FIG. 8C illustrates a right side-view of the appara