Abstract
In plasmolyzed Escherichia coli, wall and membrane adhered to one another at 200 to 400 localized areas. This number of specialized wall areas per cell was of the same order of magnitude as the total number of bacteriophage receptors. When bacteriophages T1 to T7 were adsorbed to the bacteria, they were seen to attach almost exclusively to these areas. Comparisons of the number of adsorbed phage particles observed in ultrathin sections and the expected number of phages per cell were in agreement. These results suggest a sharing of receptive areas by the various phages. Adsorption to the wall-membrane associations would permit the virus to release its nucleic acid at an area closest to the cell's protoplasmic contents.