Micro-libraries and methods of making and manipulating them methods for generating and analyzing micro-libraries

A method for generating and analyzing micro-libraries of cellular clones, comprising the steps of:

• (A) providing a population of mother cells that represents a plurality of microscopic subpopulations that differ, one from the other, by at least one genetic characteristic;
• (B) immobilizing said population such that said mother cells are retained and the approximate density of said subpopulations in said population on said surface is between 10 subpopulations per mm.sup.2 and 10.sup.6 subpopulations per mm.sup.2 ;
• then
• (C) bringing said first surface into close proximity of a second surface such that (i) daughter cells replicated from said mother cells, but not said mother cells, come into contact with and are immobilized on said second surface during the process of replication or after separating from said mother cells, and (ii) subpopulations of said daughter cells immobilized on said second surface are positioned thereon in a spatial relationship with respect to one another which is substantially similar to the spatial relationships with respect to one another of said subpopulations of mother cells immobilized on said first surface such that corresponding mother cell and daughter cell subpopulations can be identified by their similar positions in said spacial relationships on the two surfaces, thereafter
• (D) treating said second surface such that microscopic subpopulations of said daughter cells are rendered distinguishable, one from the other;
• and then
• (E) examining said second surface to detect the presence of at least one microscopic subpopulation of daughter cells.