Transition from Protozoa to Metazoa: An Experimental Approach.- 1 Introduction.- 2 Proteins Present in All Biotic Regna.- 3 Monophyly of Metazoa.- 4 Origin of Metazoan Genes and Proteins.- 5 Evolution of Metazoan Genes.- 6 Directed Evolution?.- References.- Individuality in Early Eukaryotes and the Consequences for Matazoan Development.- 1 Introduction.- 2 The Evolution of Metabolism and Development.- 3 Conclusions.- References.- Evolution of Animal Lectins.- 1 Introduction.- 2 Brief Overview of Lectins.- 3 Evolution of the C-Type Lectin Family.- 4 Evolution of Galectins.- 5 Comparison of the Galectin Family and the C-Type Lectin Family.- 6 Evolution of Glycocodes.- References.- Molecular Phylogeny of Eumetazoa: Genes in Sponges (Porifera) Give Evidence for Monophyly of Animals.- 1 Introduction.- 2 Earlier Problems.- 3 Porifera (Sponges).- 4 Rationale for a Classification of Sponges as Metazoa.- 5 Genes in Sponges: Coding for Metazoan Proteins.- 6 Evolutionary Tempo.- 7 Conclusion.- References.- Homeobox Genes in the Freshwater Sponge Ephydatia fluviatilis.- 1 Introduction.- 2 Classification of Homeobox Genes.- 3 Homeobox Genes in Freshwater Sponges.- 4 Comparison of the Homeobox Genes of Sponges with Those of Other Animals.- 5 Principles Associated with the Conservation and Diversification of Homeobox Genes During Animal Evolution.- 6 Conclusion.- References.- Homeobox-Containing Genes in Freshwater Sponges: Characterization, Expression and Phylogeny.- 1 Introduction.- 2 Materials and Methods.- 3 Results and Discussion.- 4 Conclusions.- References.- Early Evolution of the Metazoa: An Inference from the Elongation Factor-1?.- 1 Introduction.- 2 Inference from EF-1? Sequences.- 3 Monophyly of the Metazoa.- 4 Phylogenetic Status of the Diploblasts.- 5 Conclusion.-References.