ABSTRACT
Colloids can be considered as “particles” having a least diameter in the range of about 0.001 to 1.0 µm.1 The significance of the submicron size range is that an appreciable fraction of the molecules of a colloid is located at the boundary region between particle and aquatic milieu, and a microscope investigation should employ at least one microscope whose resolution permits analyses of the smallest colloids and their surfaces. The conventional transmission electron microscope, transmission electron microscopy, is currently the most useful kind of microscope for morphological analyses of colloids and aggregates of colloids. Immunocytochemistry or immunoelectron microscopy, a blend of cytochemistry and immunology, has shown some potential for the characterization of aquatic colloids. Individual colloids within an aggregate and individuals which participate in experiments on aggregation can be characterized on the basis of shape, size, native electron opacity, internal heterogeneity, porosity, and elemental composition.
