74 Miss M. P. FitzGerald. The Origin of the [June 4, 
The reaction was generally obtained in the urine, either voided during life or 
taken from the bladder after death, about 3 hours after the beginning 
of the experiment in each kind of animal. 
Taking Rabbit 7, in which case sodium ferrocyanide had been substituted for 
the potassium salt, the amount of the injection fluid given prior to the 
obtaining of the Prussian blue reaction in the voided urine was 30 c. ems. 
The weight of the animal being 1:93 kilo. (41 lbs.), this would prove the 
presence of unchanged sodium ferrocyanide in a dose representing 23:3 centi- 
grammes of sodium ferrocyanide per kilo. of body weight. The reaction was also 
obtained in the urine of the bladder after death, the total amount of the 
injection fluid received being 40 c. ems., or a dose equal to 31 centigrammes 
per kilo. of body weight. 
Dog 2, whose weight was 5°45 kilos. (12 lbs.), received 42 c. cms. of the 
potassium ferrocyanide and ammonium ferric citrate solution ; the Prussian 
blue reaction was obtained in the urine of the bladder at death 3} hours from 
the beginning of the experiment, so that evidence of untransformed potassium 
ferrocyanide was obtained in this animal after a dose equivalent to 11°5 centi- 
grammes per kilo. of body weight. 
Dating from the time of the first injection, the experiments varied in 
duration from 3 to 30 hours, and the animals were killed at times varying 
from three quarters of an hour to two hours after receiving the last injection. 
Death was caused in dogs by pithing, in rabbits by an anesthetic (chloroform ; 
in one case ether preceded chloroform), and in guinea-pigs by shock (blow 
over medulla). In every case, the stomach was removed and opened at the 
earliest possible moment after death, the mucosa exposed, and the surface of 
this, and of the contents, examined for a deposit of Prussian blue. The organ 
was then freed from the contents and placed in absolute alcohel for fixation. 
When sufficiently hard, thin vertical sections were cut by hand. 
With the exception of the spontaneous occurrence of the Prussian blue 
reaction in the skin at the site of inoculation in one or two instances, the 
tissue of the stomach alone exhibited a blue colour at the post-mortem 
examinations. Evidence of the presence of Prussian blue on the surface of 
the gastric mucosa was obtained in each kind of animal; and, in the rabbit, 
Prussian blue was also demonstrated in the lumina of the tubules, and in the 
canaliculi branching off from these into the parietal cells. 
A more complete examination of the stomach contents was made after their 
removal from the organ; extracts were made of these in distilled water, also 
of the contents of different regions of the intestines in the majority of 
cases, and the filtered fluid tested for the presence of iron salts and 
potassium ferrocyanide. In certain cases the bile was examined, but always 
