concerning Wood and Lignified cell-walls. 11 



solid cell-walls with the film of the plate, but manifests itself in 

 the cavities, suggesting that particles are thrown off from the 

 walls standing off at right angles &c. 



It seems to me that we botanists have here a definite problem 

 — or rather a series of problems. First, to see what woods, if any, 

 are totally without activity. Secondly, to find out what substances 

 in lignified cell-walls are most active. Thirdly, to try and co- 

 ordinate the results with the various degrees of lignification of the 

 walls. Further, to see if the effect is due to substances in the body 

 of the lignified walls, or to secretions or excreta left behind in 

 the cells. 



Some of the discoveries of Dr Russell appear to be of promising 

 significance — e.g. Cork is active, but pure cellulose is not ; decaying 

 wood, and wood soaked in peat (Bog Oak) may be active ; and, 

 especially, the curious intensifying action of light, for it has long 

 been known to Forest botanists that after a tree is felled, the 

 exposed heart-wood may change colour. 



Indeed, one of the first tasks I would suggest is to compare the 

 effects of fresh and old heart- and sap-woods ; of wood cut in the 

 dark and exposed to light — in or out of contact with air — and of 

 substances extracted from both heart- and sap-wood both in contact 

 with the wood itself and with pure inactive cellulose. 



Moreover these and other experiments should be made on the 

 same wood, in various conditions, as well as on species known to be 

 very active — e.g. Oak and Pine — as well as on species found to be 

 most inactive. 



It will be obvious to all that such experiments promise to 

 stimulate suggestions for other modes of attack on what has 

 hitherto proved a veritable Port Arthur to the botanist, — viz. the 

 constitution of the lignified cell-wall. 



