There has been a tremendous amount of work done throughout the years on the anatomical and physiological structure of the vitreous, and a great deal has been done toward understanding its metabolic processes. It is more difficult, however, to find much in the literature on the question of whether or not vitreous is a good culture medium. In the older textbooks of ophthalmology1 vitreous is considered to be a good culture medium, and even the more recent textbooks2 make this assumption. The rapidity with which an intraocular infection will spread through the vitreous is usually cited as evidence for this point of view. With Shafer's3 introduction of human vitreous implant as an adjunct to diathermy in the treatment of retinal detachment, there was an increase of interest in this problem. At The Eye Bank for Sight Restoration, where a program for the aspiration and storage of human