micro - scale methods are applied in producing , maintaining , replicating , screening , manipulating and sub - cloning cell libraries . by means of the micro - scale methods of the invention , micro - libraries of single - cells or micro - colonies arranged in a definite two - dimensional pattern are produced , propagated , replicated , screened , examined and manipulated . it is feasible to sub - clone cells and micro - colonies from the micro - libraries , particularly those identified by screening and examining the micro - libraries , for the purposes of purification and large - scale cultivation . automated and scaleable methods can be applied to screen practically any collection of cells attached to a surface . these methodologies are useful for making and screening on a micro - scale genomic libraries , cdna libraries , and libraries of hybridoma cells , inter alia . similar approaches employ such methods and micro - libraries for toxicological , pharmaceutical , mutagenetic and carcinogenic screening .