A model of the lysozyme crystallization process has been given by time
-resolved small-angle neutron scattering from lysozyme in a supersatur
ated solution, where larger aggregates (Type I), the radius of which i
s more than several hundred Angstrom, co-exist with a much larger numb
er of smaller particles (Type II), the radius of which is between 25 a
nd 40 Angstrom. As time elapses, the radius of the Type II particles i
ncreases, but at about 13 h, it stops increasing and starts decreasing
. Nucleation occurs here.