376 
herald the rain at R. Here the pointer, at S, 
actually gave up in despair and rested for a 
while on the stops; but it soon got free again 
and has not succumbed sinice, etc. The lag 
condition inside of the room as compared with 
those outside were well marked. At mid-day 
there is usually a slight rise of the pointer, 
owing to increased temperature and dryness. 
So far as I can see there is no reason why 
such an apparatus should not be quite trust- 
worthy. Without using mirrors, it could 
easily be made twenty times more sensitive. 
The gelatine film attached has been in the 
laboratory for at least twenty-five years under 
the same atmospheric conditions. The ques- 
tion is therefore pertinent whether we know as 
much about the continuity of thermodynamic 
equilibrium, or about colloids, as this simple 
instrument might answer. C. Barus 
Brown UNIVERSITY, 
PROVIDENCE, R. I. 
SOME ANALYSES OF THE URINE OF REPTILES 
Ir is generally stated that in the urine of 
the Sauropsida, birds and reptiles, the urea of 
the urine is replaced by uric acid, and that uric 
acid is the sole nitrogenous excretory product 
of importance. That uric acid is practically 
the sole nitrogenous constituent of the urine 
of a reptile of the arid regions, the horned liz- 
ard (Phrynosoma cornutum) of southwestern 
United States has been recently shown by the 
analyses of Weese1 from this laboratory. Ex- 
amination of the urines of some aquatic or 
semi-aquatie reptiles has indicated that uric 
acid is of less importance quantitatively in the 
urine of reptiles of this type than is generally 
assumed. 
The urine was removed from the urinary 
bladder immediately after the death of the 
animal by bleeding, and analyzed promptly. 
The use of the newer analytical methods 
(colorimetric determination of uric acid and 
creatinine (urease determination of urea) 
made possible the accurate analysis of small 
volumes of dilute urine. The specimen of alli- 
gator urine was obtained through the courtesy 
1 Weese, A. O., Scrzncz, N. S., Vol. XLVI., No. 
1195, p. 517, 1917. 
SCIENCE 
[N. S. Von. XLVIII. No. 1241 
of Professor Henry B. Ward, of the depart- 
ment of zoology. The results are expressed as 
milligrams per 100 ¢.c. urine and in the case 
of the turtles in percentages of total nitrogen. 
Alll- 
Turtle Turtle een 
Mes. | Gent. | Mes. | Gent, | Mes. 
TotalN.......,. 62 —_ 150.0; — _ 
WreaNeaecists 28 45.1 46.7} 31.1 29 
Ammonia N..... 11 17.7 21.8) 14.5 44 
Uric acid N..... 12 19.1 21.0| 14.0 47 
Creatinine N.... 1 1.6 1.4 0.9 —_ 
Creatine N...... 6 9.7 3.9 2.6 — 
It will be noted that in both of the turtle 
urines examined the amounts of urea and am- 
monia nitrogen exceed that of uric acid nitro- 
gen, the latter constituting only 19.3 and 14.0 
per cent. respectively of the total nitrogen. In 
the case of the alligator urine the uric acid 
content was somewhat higher. The relatively 
high elimination of ammonia nitrogen in com- 
parison to the amount present in most other 
types of vertebrate urine is of interest in sug- 
gesting that the uric acid may occur in the 
form of ammonia salts. The occurrence of 
creatinine and creatine or substances that give 
similar color reactions is also noteworthy. The 
relatively high content of creatine (or sub- 
stances which react similarly on hydrolysis 
and subsequent treatment with picric acid and 
alkali) was confirmed by determinations by 
both the Folin-micro and 8. R. Benedict 
methods. 
Howarp B. Lewis 
UNIVERSITY OF ILLINOIS 
SCIENCE 
A Weekly Journal devoted to the Advancement of 
Science, publishing the official notices and pro- 
ceedings of the American Association for 
the Advancement of Science 
Published every Friday by 
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