Various projects have been carried out to clarify intraocular fluid movement in rhesus monkeys. The effects of an artificial solution to substitute for aqueous humor upon the endothelium of isolated corneas were studied and found to be similar to the effects of pooled rhesus aqueous humor during storage periods of up to eight hours. This solution is now in use for ocular perfusion to determine total facility. An in vivo calibration of displaced volume during corneal applanation has been performed and compared with a similar in vitro calibration. This information is relevant to the calibrations used for human applanation tonography.