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Morphogenetic mutants of the colonial green alga, Volvox carteri f. nagariensis, were induced by chemical mutagenesis. The 68 independent mutants are classified into 12 readily identifiable phenotypes affecting various stages of asexual development. Nine of the mutants are temperature sensitive with normal development at 250 and mutant development occurring at 35°. Some mutant genes appear to be involved in the regulation of differentiation or the stability of the differentiated state. Other mutations occur in genes apparently responsible for structural components of dividing cells or adult colonies. Two mutants affect different aspects of the posterioranterior polarization of the mature colony. One mutation affects a gene which acts very early in colonial development, but affects the appearance of the mature colony. The mutants isolated demonstrate the feasibility of using Volvox to study the genetic control of early steps in embryogenesis.

The addition of 25 ,ug of protamine sulfate per ml to lysozyme-ethylenediaminetetraacetic acid spheroplasts of Escherichia coli stimulates transfection not only for Ti phage deoxyribonucleic acid (DNA; Hotz and Mauser, 1969) but also for the following phage DNA species: lambda, 10,000-fold to an efficiency of 10-3 infective centers per DNA molecule; 4X174 replicative form, 300-fold to an efficiency of 5 x 10-2; fd replicative form, 300-fold to 10-6; T7, 300-fold to 3 x 10-1. Three native phage DNA species were not infective at all in the absence of protamine sulfate but were infective in the presence of protamine sulfate with the following efficiencies: T4, 10-5; T5, 3 X 10-1; and P22, 3 X 10-9. The effect of protamine sulfate is specific for double-stranded DNA. The application of infectivity assays to the study of phage DNA replication, recombination, prophage integration, prophage excision, and interspecies transfection are discussed.