1. The Wallerian degeneration occurring in peripheral nerves by incubation in Ringer solution and serum does not occur in plasma.

2. Peripheral nerves incubated in plasma give rise to no growth. The same is true of peripheral nerves in a Wallerian degeneration up to the 4th day.

3. Peripheral nerves in Wallerian degeneration from the 5th day give rise to a growth of the syncytium of Schwann. In cultures from later stages there is a progressive growth of the same structure. It is evident that the proliferation of the cells of Schwann is directly produced by the degeneration of the axis cylinder and its myelin sheath.

4. In no case was growth of axis cylinders observed.

5. The growth of the syncytium of Schwann from degenerating nerves affords a basis for an anatomical conception of the centrifugal orientation of growing axis cylinders in regeneration.

6. Morphologically there is a striking resemblance between the syncytium of Schwann and neuroglia growing in plasma.

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