i8 7 
O'Brien . — The Proteids of Wheat . 
form, but as yet I have only been able to prepare it on a very 
small scale. The globulin is precipitated from its salt-solu- 
tion by alcohol, filtered, washed with dilute alcohol, and 
re-dissolved in salt-solution (NaCl). The process of crystallisa- 
tion can then be watched under the microscope in a drop 
of this solution. As the water evaporates, the proteid is first 
deposited on the surface of the slide in hexagonal plates. 
Usually three of the angles are formed, and then two parallel 
sides are continued for some time ; many of these forms occur 
side by side, springing from an irregular mass of proteid — 
a perfectly regular hexagonal plate is rare. Occasionally 
a large, well-defined, double hexagonal pyramid is seen, or 
what appears to be a dodecahedron with triangular faces. 
As evaporation proceeds, the salt is also deposited, either 
independently in large crystals or else in tiny cubic crystals 
covering the hexagonal areas laid down, and rendering their 
outline less distinct. Addition of water of course causes the 
proteid crystals to dissolve in the re-formed salt-solution ; 
but it is, with care, possible to fix them and so show their 
proteid nature. Fixing with alcohol was not successful — 
probably it was not allowed to act for a sufficient time. But 
if the slide with proteid and salt-crystals is placed in a con- 
centrated solution of tannic acid, the salt dissolves whilst the 
proteid is fixed. After careful washing the hexagonal proteid 
plates remain on the slide, and the pyramidal crystals retain 
their outline though with a slightly contracted and collapsed 
appearance. With a saturated solution of picric acid similar 
results may be obtained, though with greater difficulty, as 
much care is required in washing away the excess of picric 
acid. Similar proteid crystals were incidentally observed on 
a slide on which a section of barley had been left in salt- 
solution. 
The tendency to crystallisation seems strong. Precipitated 
by alcohol, globulin separates in minute, irregular, flake-like 
forms, from which, by treatment with NaCl on a slide or in 
a watch-glass, crystalline forms may be obtained. Coagulated 
by boiling, globulin settles out in spheres embedded in a more 
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