-11- 
All the syringe parte are shown In flgxire 7, and the struotural 
details of the tips and plvmger are given in figure 8* Sinoe the neaaore* 
nents and details of construotion of the housing^ turning screw, oouplings, 
and supplemental rod are of secondary importanoe, they will zu>t be described. 
Their approximate else can be ascertained from the pict\u*e# The uniynrsal 
Joint between the turning screw and the supplemental rod allows the metal 
plunger to move within the tip without rotating. Lack of rotation reduces 
wear ejod gives better suction* 
The tip is made from a Lucite rod of 0«1875-inch diameter* This rod 
is placed in the machine and drilled to a depth of about 1 inch with a 
No. 72 (0.025 inch) drill, A smaller drill--No.79 (0,0145 inch)— provided 
with a long shank is then used to drill an additional 0*1 inch in the 
bottom of the 0.025-'inch hole* The outside diameter is then turned down 
to 0*164 inch, and the end threaded for a distance of about 0.26 inch with 
an 8-<32 threading die* Before the rod is removed from the machine, its 
diameter between the threaded portion and the end of the drilled portion 
can be reduced to the approximate site of the main portion of the tip 
(0*085 inch). 
The end of the tip containing the small hole is then rotated on an 
electric soldering iron imtil it becomes soft enough to stretch. This 
0*l»inch section with the 0«0145-inch bore is then stretched to a length 
of 0.2 to 0*25 inch and, while still held taut, is hardened in cold water* 
If the rod is properly heated, the 0*025-inoh hole is not distorted* The 
0*0145-inoh hole becomes a gi*adual taper from that diameter down to less 
than 0.006 inch* The end of the tip is then filed off square, and the 
outside diameter reduced to 0*012 inch* No* 2 cut files can be vised to 
reduce the diameter to near sire, but the polishing should be done with 
9/0 production finishing paper* The final polish may be obtained by rub- 
bing with moistened cigar ash* 
The plunger can be made from brass spring wire of 0.025* inch dia- 
meter* It must be straight and miiformly round without snarp edges. 
The butt end is soldered into a 0*0625-inch brass rod which has been 
threaded to screw into the supplemental rod of the syringe* 
Holding Hooks 
The function of the holding hooks is to hold the sting chamber open 
and the sting back out of the way dxu*ing the operation* The ventral hook 
(figs. 1 and 4, VH; fig, 9) fits over the T«ntral plate* It is constructed 
of a piece of No* 24 gage brass wire slightly flattened at the end, and 
bent as illustrated in figure 9* The distance from the bottom of the U to 
the tip is 2.5 mm*, and the distance between the inside walls of the U is 
0*37 mm* The tip of the ventral plate fits into the U-shaped portion so 
that the plate remains in a vertical position as it is pulled ventrally 
by the hook* 
The dorsal or sting hook (figs* 1 and 4, STF j fig. 9) is designed to 
pull the entire sting mechanism dorsally. 1 similar instrument was used 
by Laidlaw (2^). It has an enlargement at the end, which fits into the 
