Leukemia, Lymphoid/classification; Lymphoma/classification; T-Lymphocytes; Animals; Chromosome Aberrations; Chromosomes, Human, 1-3/ultrastructure; Chromosomes, Human, 13-15/ultrastructure; Chromosomes, Human, 6-12 and X/ultrastructure; Clone Cells/pathology; Deltaretrovirus/isolation & purification; Deltaretrovirus/pathogenicity; Granulocytes/pathology; Haplorhini/microbiology; Humans; Leukemia, Lymphoid/etiology; Leukemia, Lymphoid/genetics; Leukemia, Lymphoid/microbiology; Lymphoma/etiology; Lymphoma/genetics; Lymphoma/microbiology; Lymphoproliferative Disorders/classification; Oncogenes; Retroviridae Infections/complications; Retroviridae Infections/genetics; T-Lymphocytes/classification; T-Lymphocytes/pathology; T-Lymphocytes/ultrastructure; T-Lymphocytes, Helper-Inducer