BULLETIN OF THE BUSSEY INSTITUTION. 269 
at the broadest point. Twenty-five of these cylinders taken to- 
gether weighed 1.65 grm. Whereas, on examining a quantity of 
normal, dark-colored mouse-dung taken from a cellar-shelf, — as 
well as that voided by the mice when first caught, — it appeared 
that such cylinders were usually about 6 mm. long, though some- 
times no more than 3 mm., and about 2 mm. thick. One hundred 
of these old dry cylinders weighed 0.87 grm. 
The contrast between the dung voided by the mice when they 
were fed with putty and directly afterward, at the time when balls 
made from whiting and water were offered them, was very strik- 
ing. During the latter period the cylinders were only 3 or 4 mm. 
long and about 14 mm. thick; and 25 of these little cylinders 
weighed only 0.16 grm., which is no more than the weight of 24 of 
the great cylinders voided at the time of the putty ration. 
But the most surprising point in connection with the white dung 
is the small amount of oil that has been left in it. The dung of 
the putty-fed mice was friablesand crumbly. When pressed with 
the blade of a knife it seemed to be no more plastic than pure 
whiting to which no oil had ever been added; and on extracting 
the dung with ether it appeared that it contained no oil, or as good 
as none. For the sake of comparison two grammes of the white 
dung were leached with ether in one tube, while two-tenths of a 
gramme of the original putty were leached in precisely the same 
way in another tube. The ;2; grm. of putty yielded much oil, but 
the 2 grms. of dung gave only some small traces of what appeared 
to be biliary matter rather than oil. 
It is interesting to compare this experiment with the observation 
of Gustav Meyer* in his experiments upon the digestibility of 
coarse bread, since it shows that the tendency of indigestible mat- 
ter to pass rapidly through the intestinal canal may not be suf- 
ficiently marked in all cases to prevent the digestion of a substance 
possessing the chemical properties and the mobility of oil; although, 
as Meyer has shown, the inert portions of coarse bread work very 
decidedly to prevent the digestion of some of the constituents 
of that kind of food, both by causing rapid evacuation of the in- 
testines and by enveloping the digestible matters. t 
* «¢ Zeitschrift fiir Biologie,” 1871, T. pp. 28, 48. 
+ Since the above was written, the experiments of Rubner (‘‘ Zeitschrift 
fiir Biologie,” 1879, 15. pp. 115, 188) have shown that, as a general rule, fat 
is pretty thoroughly absorbed from the intestines of men, even when it has 
been eaten at the same time with some tolerably bulky foods. 
