6 
These slig’ht modilications in the construction of the syringe are 
intended to facilitate its use as well as to increase its accuracy. The 
way of using these sjudnges ditfers so manifestly from any known to 
me that I will describe it in detail, for the precision depends as much 
upon the method of using them as upon their construction. 
The glass barrels are cleaned in a saturated solution of chromic acid 
in sulphuric acid which leayes them chemically clean and preyents 
water or other fluids sticking to the glass in large drops. The acid is 
thoroughly washed out with tap water and then flushed in distilled 
water, allowed to dry and sterilized by dry heat. Clean glass allows 
a free flow, diminishing the amount of water which adheres to the 
surface, and thereby helps to thoroughly empty the contents. 
The needles are sterilized separately by the usual method of boiling 
in a 1 per cent sodium carbonate solution. 
The needle is now screwed on the barrel of the syringe and the 
joint tested by drawing some sterile salt solution in and out seyeral 
times. If the joint is tight and the needle peryious, the outside is dried 
with a little piece of sterile gauze, and the needle is now plunged into 
a jar of sterilized albolene. The albolene acts as a temporary plug, 
preyenting aii}^ of the fluid which is placed in the syringe from escap- 
ing until it is injected into the animal. 
The necessary number of s}u-inges are prepared, one for each ani- 
mal. In testing diphtheria toxin and antitoxin we sometimes haye a 
batter}' of ten, twenty, or thirty syringes thus prepared, arranged on 
the rack as shown in the accompanying diagram. (Fig. 1.) 
The amount of fluid desired to inject into the animal is now carefulh' 
measured directly into the barrel of the syringe. This is injected into 
the animal, and then without withdrawing the needle the bulb is 
remoyed: a few cubic centimeters of salt solution are quickly blown 
into the barrel, washing down the sides, and this in turn is injected 
into the animal. 
The syringes can not be turned oyer, as is the case with a piston 
syringe. It is not necessary, howeyer, to hold them upright, as might 
at tirst be imagined. They may be tilted to a greater angle than 15^ . 
without danger of the fluid running out. 
The rack in which the syringes are shown (tig. 1) is made of wood 
and has seyeral conyeniences worth noting. The bottom shelf is of 
glass. The least drop through the needle or from a leaky joint is 
plainly seen on the glass, which acts as a telltale against this possible 
error. 
I also write upon the glass plate the amount each syringe is to 
receiye, which helps to ayoid mistakes and facilitates the work. 
Each glass barrel is numbered with the number of the experiment 
or of the animal to receiye the injection. This is yery conyenient and 
ayoids confusion. 
