1891.] MICROSCOPICAL JOURNAL. 41 



Beale, as in subsequent staining with the ammonia carbonate, unless 

 tlie blue injection is distinctly acid, all its color becomes degraded, or 

 almost lost after a few years, by the alkalinity of the carmine stain. 



Red transparent injections are also recommended as instructive and 

 pretty. The formula given by Dr. Beale will be found to work well, 

 but as it contains gelatine, both subject and solution must be kept warm. 

 Pure carmine, one drachm ; liquor ammonia, two drachms ; glacial ace- 

 tic acid, one di^achm 36, minims; solution of gelatine (i part to 6 of 

 water), two ounces; water, i^ ounces. Dissolve the carmine in the 

 ammonia and water, and filter if necessary. To this add an ounce and 

 a half of the hot solution of gelatine and mix thoroughly. With the 

 remaining half ounce of gelatine solution mix the acetic acid, and then 

 drop this little by little into the carmine solution, stirring briskly during 

 the whole time. Great care is retjuired in mixing this injection that no 

 precipitation of the carmine takes place by putting in the acid in too 

 large quantities at a time ; and therefore, while mixing, a little should 

 be examined under the microscope, and the addition of the acid solution 

 discontinued in time, should signs of precipitation appear. In carrying 

 out this process there is one condition not to be overlooked, and which, 

 if neglected, will only end in failure, or, at the best, only partial injec- 

 tion. The animal must be freshly killed, and injection commenced 

 before rigor mortis sets in, as the rigidity of the coats of the capillaries 

 will prevent that smooth flow of the injecting fluid which is conducive 

 to a satisfactory result. 



An Inject ing Syringe. — This is a syringe of brass of about two- 

 ounce capacity, having a well-fitted piston working easily, but not too 

 freely, the handle of which is formed of a ring sufficiently large to allow 

 the thumb to pass through, and two rings in which the fingers are placed. 



Nozzles. — These, when in use, are firmly fixed to the end of the 

 syringe, and are generally supplied in three or more sizes to accommo- 

 date the varying calibres of the vessels to be injected. 



A difterent apparatus renders the operation much less fatiguing and 

 will commend itself as less likely to end in failure from too much force 

 being applied by the hand in syringe injecting. This arrangement con- 

 sists in two Woolf's bottles placed on a shelf about five feet above the 

 laboratory table ; one of these is partially filled with the injection fluid, 

 and the other with warm weak solution of table salt in water. A bent 

 glass tube, inserted through a cork in one of the necks of the bottle, 

 passing to the bottom acts as a syphon. Two lengths of India rubber 

 tubing and of sufficient length to reach the table should be well washed 

 out, to free them from the particles found in all new tubing. In the 

 free end of each length of tubing is fastened such a stop-cock as is gen- 

 erally supplied with the syringe. A tube may now be attached to the 

 short end of each glass tube. The tube may be now sucked by the 

 mouth till the fluid in the bottle begins to flow down the tube. When 

 it runs out, the stop-cock must be turned ofl\ This is done to prevent 

 any air getting ingress to the vessels. That contingency must ever be 

 guarded against as fraught with danger to the success of the operation. 

 We have now two tubes filled with the fluid, and constituting a column 

 whose weight is sufficient to overcome the resistance of the vessels. 

 Now commence operations at the heart ; but before doing so sunilry 

 accessory appliances should be provided. A nozzle should be selected 

 as near the size of the aorta as possible. The nozzles have two pro- 



