filtered off and the filtrate concentrated in vacuo over sulphuric 
acid to a small bulk, it still gives the Piotrowsky’s reaction, though 
more feebly. The presence of both albumins and globulins is there- 
fore indicated. Their presence is proved further by the separation 
with ammonium sulphate. Half saturation (in a capillary tube) 
gives a precipitate which when filtered offand drawn into a wider 
capillary tube and mixed with about six times its bulk of saturated 
ammonium sulphate solution yields a further precipitate. After 
this is removed by filtration, the filtrate on concentration and re- 
filtration is found to contain neither propeptones nor peptones, 
which are therefore absent from the original fluid. 
Pigment. — When the liquid is added to about twelve times its 
bulk of alcohol, the whole of the proteins are precipitated as a 
white coherent mass, and the pigments are retained in the alcoholic 
supernatant fluid, which becomes yellow. Similar results are given 
with ether, except that the proteins are only partially coagulated, 
and form with the water and inorganic constituents a pasty mass 
at the bottom of the narrow tube. 
The alcoholic solution, when spectroscopically examined, exhi- 
bits no definite bands in the visible spectrum; a diffuse absorption 
of the violet end, and to a less extent of the extreme red, being all 
that can be observed. In all probability, therefore, the colouring 
matter is a lipochrome. This is borne out by two other characters, 
NZ: 
1. The ethereal solution is bleached when exposed to sunlight; 
2. When excess of strong nitric acid is added to the fresh secre- 
tion, the colour changes to an evanescent azure blue, turning to a 
dirty greenish grey. 
Lipochromes are therefore at all events the chief pigments. 
It seems possible also that other pigments may be present. Thus 
if the secretion be dropped upon a filter-paper and dried at the 
ordinary temperature, a brown stain is left; if the stained paper be 
now extracted with dry ether, the lipochromes are removed and 
dissolved in the ether, but the stain remains and shows a greenish 
tinge, which on exposure to light for some days vanishes. 
Other constituents. — When a column of the liquid is mixed in 
a capillary tube with sodium hypobromite solution, bubbles of gas 
very soon make their appearance, suggesting the presence of urea 
