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Addendum: Skin Tumors and Lymphomas in Hamsters 
Graffi and his coworkers inoculated newborn hamsters with normal hamster 
embryo cell cultures and observed the development in 80 hamsters of multiple 
wart-like skin tumors originating from hair follicles. Electron microscopic 
examination revealed in the nuclei of the tumor cells the presence of crystalline 
arrays of virus particles about 35 mju in diameter; occasionally, particles were also 
found in the cytoplasm and in intercellular spaces (Graffi, A., Schramm, T., 
Bender, E., Bierwolf, D., and Graffi, I., t)ber einen virushaltigen Hauttumor 
beim Goldhamster. Arch. Gesclnvufstforsch., 30: 277-283, 1967). When an attempt 
was made to transmit these skin tumors by filtrates to newborn hamsters, lym- 
phomas developed in 45 per cent of the inoculated animals; reticulum-cell 
sarcomas were also induced when centrifuged skin tumor extracts were' inoculated 
into newborn Wistar rats. Electron microscopic examination of the hamster 
lymphomas revealed in the cytoplasm a small number of spherical virus particles, 
about 90 to 100 mp in diameter; some particles were budding from the membrane 
of the endoplasmic reticulum. The lymphomas induced either in hamsters or in 
rats could be transmitted by filtrates to newborn hamsters, reproducing the same 
disease (Graffi, A., Schramm, T., Bender, E., Graffi, I., Horn, K.-H., and 
Bierwolf, D., Cell-free transmissible leukoses in Syrian hamsters, probably of 
viral aetiology. Bril. J. Cancer, 22: 577—581, 1968). 
[Appendix C— 167] 
