24 
Between 9 and 10 a. m.. October 17. the animal passed another por- 
tion of clear urine. This also was normal in appearance and gave no 
evidence of phenolphthalein on the simple addition of caustic soda, 
but on boiling with dilute hydrochloric acid the acid solution of the 
urine took on a very decided blue color, and on cooling and making 
alkaline with caustic soda the characteristic purplish-red coloration 
of phenolphthalein in alkali was obtained. From this time on until 
November 20. 1905. the urine of this pig was tested several times 
each day in the manner already described, using from 1 to 5 c.c. 
of the urine for each test. At no time, however, during this inter- 
val did the urine show more than the faintest trace of pink color on 
the addition of caustic soda direct and frequently none at all. On 
boiling the specimen with dilute hydrochloric acid, however, and then 
adding caustic soda a very decided purplish-red coloration was 
obtained with each sample of urine for a period of nineteen days, and 
distinct traces of the phenolphthalein compound were recognizable in 
the urine as late as November 20, 1905. 
In order to determine whether any phenolphthalein is reduced in the 
organism a specimen of the urine of pig (1), which was nearly color- 
less. was filtered and divided into two equal portions. To one of these 
(1) there was added 0.5 cc. of water, and to the second (2) 0.5 cc. of a 
solution of potassium ferricyanide. To each of these solutions 0.3 cc. 
of 2N sodium hvdroxide was then added. The color change brought 
about by the addition of the sodium hydroxide to (1) was very slight, 
whereas in the case of (2) the solution became distinctly reddish, indi- 
cating the presence in the urine of a leuco-compound oxidizable by 
potassium ferricyanide. This substance in all probability is phenol- 
phthalin. Compared with the amount of phenolphthalein. however, 
which is recoverable from the urine bv hvdrolvzing it with hvdro- 
chloric acid, the quantity which is reduced to phenolphthalin in the 
organism is practically negligible. 
THE CONDUCT OF OTHER PHTHALEIX3 IX THE ANIMAL ORGANISM. 
Fluorescein . — The conduct of fluorescein in the animal organism was 
also tested on a guinea pig in the following manner: 0.5 gram of 
fluorescein, suspended in water, was injected into the peritoneal cavity 
of a guinea pig weighing 455 grams at 2 p. m., October 17, 1905. In 
less than an hour the animal was completely prostrated and showed a 
tendency to convulsive movements. The animal died at 3.15 p. m. of 
the same day. Sometime after the injection the eyes of the pig- 
exhibited a marked greenish fluorescence. 
The post-mortem examination showed all of the internal organs to be 
stronglv colored with fluorescein. The skin also was greenish vellow 
and all parts of the eye contained fluorescein, except the crystalline 
lens. The peritoneal cavity contained considerable fluid. The blad- 
