-15- 
The function of the air bubble is to prevent the mixing of semen 
and water and to mark the boxmdary between them so that diluted semen will 
not be injected. As injection proceeds semen adheres to the side walls 
and mixes with the water which follows, so that in the absence of an air 
bubble it is difficult to distinguish between pure and diluted semen, 
iihen a series of inseminations is made without the syringe being cleaned, 
as is possible with the plastic syringe, the air bubble is superfluous o 
Injection 
As soon as the syritige is filled, the point is moistened to prevent 
clogging by drying of semen and to lubricate it. The syringe is moved 
into position over the queen and the microscope pushed forward so that 
the queen is in the field and the magnification changed to high power. 
The sting hook is then drawn dorsally xintil the sting chamber appears as 
in figure 1. This act stretches the loose membranes so that the vaginal 
orifice, and often the valvefold, are visible o It also stretches the 
dorsal wall of the vagina so that the syringe can slide along it into the 
median oviduct. 
Vifith the left hand the probe is inserted into the dorsal part of the 
vagina and the valvefold pushed ventrally, until the point of the syringe 
has passed beyond. Then, as the syringe is pushed in farther, the probe 
is removed • The syringe should be inserted no farther beyond the valve- 
fold than is necessary for satisfactory insemination (about 1 to 1.5 mm.). 
The plastic tip can be inserted deeper than the glass tip on account of 
its more gradvially tapering point. If it appears that the syringe carries 
tissue in with it as if caugjht on the end of the syringe, then the point 
has not hit th6 median oviduct and should be withdrawn and reinserted, 
possibly after some readjustment of the holding hooks. 
Tfiith the syringe in place the plunger is slowly pushed downward. 
If the semen moves down the barrel easily and does not leak out around the 
point, then the syringe is in proper position and the injection can proceed 
rapidly. If the glass syringe is used, great care must be exercised that 
the plunger never reaches the cone-shaped point. The plunger of the plas- 
tic syringe, on the other hand, can be pushed to the end of the larger 
bore without danger of breakage • 
The syringe is now withdrawn from the queen, and then from its box, 
the spring being depressed with forceps so that the syringe slips out 
easily without danger of the point breaking. Removal of the queen from 
her holder completes the operation. 
Cleaning the Syringe 
The glass syringe should be cleaned immediately, by alternately draw- 
ing in and expelling fresh water until the liquid inside the syringe is 
relatively clear. ^Vhen the plunger does not fit closely, a little semen 
left in the liquid may help to increase suction. 
„,„•»■'»*«' 
