Records of the jump of Galago senegalensis are subjective and incomplete. Observation of the jump confirms the findings of previous authors but its suddenness and speed preclude any detailed account of the important period during which the animal maintains contact with the ground. Using high-speed cinematography an analysis has been made of movement during this period. This photographic analysis provides sufficient data for estimates to be made of the tensions that the muscle groups concerned are required to develop and the distances over which they need to shorten.
(1) An account is given of observations made of the jump of G. senegalensis in the field and in captivity.
(2) A standing vertical jump of 7 feet 43/4 inches is recorded.
(3) A photographic analysis of the earliest stages of the jump reveals (a) that the fore-limbs take little part, (b) that effective use is made of the length of the synchronously acting hind limbs, and (c) that force is applied to the ground in the region of the tarsometatarsal joint.
(4) A mechanical analysis provides estimates of the tensions expected to be developed by the quadriceps femoris and triceps surae muscle groups and shows that in the act of jumping the gastrocnemius requires to shorten only a small amount in order to produce a full excursion of the ankle joint.