1. - Vesicles and pustules containing numerous cytoplasmic inclusion bodies within the epidermal cells were regularly produced in monkeys (Macacus rhesus) by intravenous inoculation either of alastrim virus or of recently prepared vaccine emulsion, no previous scarifications being required. Alastrim virus seems less virulent for this species of monkey than the virus of vaccinia is. While 12 rhesus monkeys injected intravenously with seven strains of alastrim virus developed regularly an experimental infection and finally recovered and remained well, the intravenous injection of vaccine virus was followed by death in two from four rhesus monkeys injected. 2. Slight but definite and regular differences were noticed between alastrim and vaccine bodies after fixation in Helly's fluid, embedding in paraffin and staining with alum hematoxylin and eosin. They are related to the number of inclusions within the cell and to their staining. 3. - In each cell of the epidermis of Macacus rhesus there is usually a single alastrim body when late stages are considered, and quite a few (2-4) when early stages are observed. Alastrim bodies stain a deep blue to grayish-blue. Nevertheless, in necrotic epidermal cells or in cells provided with a few small inclusions they sometimes present a pink staining. 4. - Vaccine bodies in late stages of development are numerous in each epidermal cell of the rhesus monkey and present regularly a characteristic polychromatophilia.