196 TIMBER AND SOME OF ITS DISEASES. [CHAP. 



emitted their germinal hyphae, and commenced to 

 form the mycelium. This may or may not be the 

 case : the important point is simply that the fungus is 

 already there. Having arrived at the timber-wharves 

 the logs are stacked for sawing in heaps as big as 

 houses : after a time the sawing up begins. It usually 

 happens that the uppermost logs when cut up show 

 little or no signs of rot ; lower down, however, red and 

 brown streaks appear in the planks, and when the 

 lowermost logs are reached, perhaps after some weeks 

 or months, deep channels of powdery, rotten wood are 

 found, running up inside the logs in such a way that 

 their transverse sections often form triangular or 

 Y-shaped figures, with the apex of the triangle or V 

 turned towards the periphery of the log. 



The explanation is simple. The uppermost logs 

 on the stack have dried sufficiently to arrest the 

 progress of the mycelium, and therefore of the 

 disease : the lower logs, however, kept damp and 

 warm by those above, have offered every chance to 

 the formation and spread of the mycelium deep 

 down in the cracks of the timber. I was much im- 

 pressed with this ingenious explanation, first given 

 to me by Prof. Hartig, and illustrated by actual 

 specimens. It will be noticed how fully it explains 

 the curious shape of the rotten courses because the 



