62 QUEENSLAND AGRICULTURAL JOURNAL. [1 Jaw., 1899. 
second place, that itis impossible to introduce the required amount of blood. 
The blood having been transferred from the syringe to the beast, the operation 
is complete. Itisnot necessary to take the temperatures of the animals after- 
wards, as if proper blood is used the inoculation seldom fails. 
SPECIAL NOTHS ON THE INSTRUMENTS AND THEIR USE. 
THE TROCAR AND CANULA. . 
When using the trocar, special care should be exercised that the canula is 
not shifted forward beyond the little shoulder of the point of the trocar; 
otherwise the greatest difficulty will be experienced when endeavouring to insert 
the trocar into the vein. 
It will be noticed that the trocar has three cutting edges at its point; 
therefore if it is thrust into the vein without using any screwing motion, it 
will push with it three little triangular flaps of the wall of the bloodvessel, 
which press against the outer sides of the canula; consequently, after having 
obtained the required amount of blood, the canula is withdrawn, and the three 
little flaps, being of an elastic nature, are iunmediately brought into their 
normal position, and act as valves, in consequence of the pressure of blood 
- within the vein, thereby preventing the blood from escaping. In this method 
there is no tying or stitching of the skin, as is the case when the operation of 
bleeding is performed by means of the fleam, an instrument which has now 
become almost obsolete. 
To facilitate the introduction of the trocar, the skin of the neck above the 
vein can be cut nearly through beforehand with a sharp knife. 
THE HYPODERMIC SYRINGE. 
The reason why a syringe hoiding 10 ¢.c. is recommended, when only half 
the quantity—viz., 5 e.c.—is a standard dose for each animal, is that frequently 
when filling the syringe a bubble of air gets inside. This does not matter in 
the least, for by making it a golden rule when inoculating to always hold the 
syringe in a slanting position, with the nozzle downwards, the exact quantity of 
blood only is injected, while the remaining blood plus the air-bubble are kept 
back in the syringe. 
THE IMPROVED DOUBLE-ACTION VALVE APPARATUS. 
This accessory is only required when hundreds of cattle are being put 
through in a day. The improved valves are arranged on exactly the same 
principle as the valves of a force-pump, so that, at every drawing motion of the 
plunger, the valve controlling the suction or reservoir tube is opened, and the 
valve of the delivery or injection tube is closed, the syringe being thus filled, 
while at any pressure of the piunger the suction-vaive is closed, and the 
delivery-valve opened. The blood, once it has left the supply-bottle, cannot 
be returned to it through the tube, but can only be ejected through the long 
tube to the point of the hollow needle, so that, when’ the needle is placed in 
position under the skin of an animal, that animal must infallibly receive an — 
injection of blood when the plunger of the piston-rod is pressed home. 
The short piece of rubber tubing connecting the suction-valve is held in ~ 
proper position by a cork with a V-shaped piece cut out of its side lengthwise, 
and fitted into the neck of the bottle. 
The syringe fitted with the improved valve and long tubing has many 
advantages :— ; 
1. There is no possible danger to the syringe or the bottle of blood, as 
the operator in charge of same is enabled by means of the long 
piece of tubing to stand quite clear of the crush and the cattle to 
be inoculated. 
2. The man in charge of the needle has nothing more to do than see 
that it is properly inserted under the skin of the animal, give the 
signal, and, after the blood is injected, withdraw the needle, and fix 
it in another animal. 
