THE PURPOSE of this paper is to clarify the long-debated problem of the true nature of a corneal graft. The crux of the problem is whether a corneal graft heals like a skin graft, in other words like a "true" graft, or like a boiled bone or preserved cartilage graft, often called a "replacement" graft.
The previous work on cultures of corneal tissue has shown that the cells of the corneal stroma have the ability to divide and migrate.1 With this in mind, it was felt that if a corneal graft were a "true" graft then donor cornea the cells of which had been "activated" by growth in tissue culture should heal rapidly in the recipient cornea. Accordingly, pieces of donor cornea were grown in tissue culture for varying lengths of time and then transplanted into the recipient corneas. Instead of rapid healing, all eyes revealed a marked repellent