In many cases longitudinal splits occur which isolate bundles of elements by greater or less intervals.

The splitting occurs by a tearing of the fibres or rays and not by the separation of the rays from the adjacent elements.
[Illustration: FIG.

8 .-- Failures of short columns of green spruce.] [Illustration: FIG.

9 .-- Failures of short columns of dry chestnut.] Moisture in wood decreases the stiffness of the fibre walls and enlarges the region of failure.

The curve which the fibre walls make in the region of failure is more gradual and also more irregular than in dry wood, and the fibres are more likely to be separated.
In examining the lines of rupture in compression parallel to the grain it appears that there does not exist any specific type, that is, one that is characteristic of all woods.