Kirk. — On Starch and Glucose in Timber. 379 



Art. XL. — On the Occurrence of Starch and Glucose in Timber. 



By H. B. Kirk, M.A., Professor of Biology in Victoria 

 College, Wellington. 

 [Read before the Wellington Philosophical Society, \%th April, 1904.] 

 In the course of work on the histological character of New Zea- 

 land timbers, I was struck with the frequency with which starch 

 is found in kahikatea or white-pine (Podocarpus dacrydioides). 

 It seemed that this might have some connection with the peculiar 

 liability of white-pine to be attacked by the boring larva of a 

 beetle, and I was led to examine as many specimens as possible 

 of worm-eaten timber of this kind. The result was that in nearly 

 every case in which the timber was so attacked starch was found 

 to be present either in the medullary rays or in the xylem paren- 

 chyma, and the few samples of worm-eaten white-pine that did 

 not contain starch contained abundant glucose. 



In a paper read before the Australasian Association for the 

 Advancement of Science, in January of this year, I suggested 

 that kahikatea might always be relied on to yield the satisfactory 

 results that it has sometimes been found to yield, if it were cut 

 when the stored starch has been converted into soluble glucose 

 for the use of the plant, and if the converted timber were allowed 

 to remain for some time exposed to the action of water to dis- 

 solve out the glucose. With the kind assistance of Mr. Holmes, 

 of the Public Works Department, and of others, I am endea- 

 vouring to determine at what time starch ordinarily disappears 

 from the tissues. 



Since January I have examined many other samples of worm- 

 eaten timber, and find that timber attacked by larva? of beetles 

 contains either starch or glucose, usually the former. Of course 

 my observations are not at present by any means exhaustive, 

 and there is in all cases great difficulty in ascertaining with any 

 certainty even the approximate time at which the timber was 

 felled. Excluding kahikatea, the samples noted here have been 

 examined. 



Rimu (Dacrydium cupressinum) : Worm-eaten samples usually 

 contain starch both in rays and in xylem parenchyma. When 

 starch is absent much glucose is present. Five samples. 



Matai (Podocarpus spicata) : As in the case of rimu. Four 

 samples. 



Totara (Podocarpus totara) : Two samples. No starch, abun- 

 dant glucose. 



Kauri (Agathis australis) : Seldom attacked. The two samples 

 are both from buildings in which there is much worm-eaten 

 kahikatea. One contains starch in the medullary rays ; the 

 other contains much glucose. 



