492 Philippine Journal of Science 1919 
thus formed the magnesium is precipitated as NH:MgPO,, the calcium as 
Ca; (PO,)2 and calcium oxalate and ammonium urate are also thrown down, 
so that the concretions consist of a mixture of these substances, the magne- 
sium salts being the most abundant.’’ He then goes on to say that “the 
formation of phosphatic concretions is always a matter of urinary reaction 
and not of diet.” 
Due to lack of data ag to the reaction of the urines before the 
onset of the disease, the present urine examinations are to be 
correlated with the chemical composition of the cortex or outside 
layer of the stones. In my series there are cases of alkaline 
urine where the stone is covered with uric acid or urate cortex. 
The latter phenomenon may be explained by the presence of 
inorganic phosphates, or by the fact that the alkaline fermenta- 
tion has not yet been brought to completeness. The opposite 
condition may be true with the phosphate or carbonate stone 
in an acid medium. The neutral urine, on the other hand, may 
be a transitional stage in the process of ammoniacal fermen- 
tation in the urine brought about by infection, or may result 
from the so-called “alkaline tide.” That food influences the 
reaction of the urine is shown by Blatherwick, who states: 
In general, foods yielding an alkaline ash were found to decrease urinary 
_ acidity, while those yielding an acid residue increased it. 
The urine of Filipinos is normally less acid than that of Amer- 
icans or Europeans, owing chiefly to the low protein content 
of their diet, which consists chiefly of rice and a little fish 
among the poorer classes. The reaction of the urine from the 
cases on admission to the hospital may be compared with the 
composition of the cortices of the calculi in. forty-nine cases 
of the series. Thus there were found in acid urines nine phos- 
phate and nine urate or uric-acid cortices and one oxalate cortex; 
in alkaline or neutral urines, there were twenty-three phosphate 
and four uric-acid or urate cortices, one oxalate cortex, and one 
oxalate and phosphate cortex. The results show a tendency 
toward the formation of phosphate concretions in neutral or 
alkaline urines in accord with the literature. 
Taking the composition of the nuclei of the stones for com- 
parative reference in regard to the age when the first symptoms 
of cystolithiasis developed (which may not coincide with the 
exact date of the beginning of the formation of the urinary 
stone), we have Table IV. 
We notice that among these fifty-eight cases there was a 
greater incidence of stone formation in children and young adults, 
contrary to the opinion of Bugbee,(5) who found a greater fre- 
quency of vesical calculi among patients past middle life. It 
