We compared four bacteriophage species, T5, lambda, T7, and Phi 29, to explore the possibilities of DNA reorganization in the capsid where the chain is highly concentrated and confined. First, we did not detect any change in DNA organization as a function of temperature between 20 to 40 degrees C. Second, the presence :of spermine (4+) induces a significant enlargement of the typical size of the hexagonal domains in all phages. We interpret these changes as a reorganization of DNA by slight movements of defects in the structure, triggered by a partial screening of repulsive interactions. We did not detect any signal characteristic of a long-range chiral organization of the encapsidated DNA in the presence and in the absence of spermine.