OBSERVATIONS UPON THE PHENOMENA OF PLANT-LIFE. 319 



be conducted only by the tissues of the bark, or the imperfectly-developed 

 tissues of the cambium between it and the perfectly formed wood. Neverthe- 

 less, there is free communication in a transverse direction for the crude sap 

 and for some of the elaborated substances between the wood and the bark, 

 probably by means of the medullary rays which connect the two. Thus only 

 can we account for the fact that the bark below a girdled place remains alive 

 long after the deposition of wood ceases, and also for the circumstance that 

 starch and sugar, which must originally come from the leaves, are found either 

 accumulated in the cells of certain stems and roots, or existing in the sap 

 which flows or is expressed from their tissues. If we shave off, little by little, 

 the bark of a maple when the sap is flowing freely, we shall observe no exu- 

 dation from any portion of the liber, even, but as soon as the whole of this is 

 removed, the sap issues from every ])art of the surface. 



Again, those who work with mill-logs tell ns that in the spring the bark 

 becomes soft and loose, precisely as if the tree was standing, at least in the case 

 of some species. Sometimes logs and poles, cut for fences, will sprout and 

 actually produce shoots with foliage, the sap of which must be derived wholly 

 from the timber, and must, therefore, pass from the wood to the bark. 



]\[r. Wm. F. Flint has sent us a piece of a red maple slab, which he found on 

 moist ground, under a pile of wood, and which had throAvn out at the end 

 and sides a callous a quarter of an inch thick, precisely like an ordinary cutting 

 of a grape vine. Here we have an instance of growth without either roots, 

 buds, or leaves, all the material for which must have been derived from the 

 stick itself. 



A CURIOUS CIRCUMSTANCE. 



Similar to this in character is the curious circumstance, not very unfrequent, 

 of old potatoes resolving themselves into several smaller ones, within the skin 

 of the parent tuber, without any external appearance of vegetation. This is 

 reported to have occurred in a vast number of tubers, in a quantity of potatoes 

 on board a vessel in the Arctic ocean, where the low temperature probably 

 exerted some influence in causing this peculiar made of sprouting. 



AIN" EXCELLENT DEMONSTRATION 



of the transverse diffusion of sap was obtained in some experiments performed 

 to observe the result of protecting girdled places on trees from the efiects of 

 exposure. Healthy young trees, or large branches, of elm, chestnut, apple, 

 grape, and white pine were drawn through glass tubes, two inches in diameter 

 and two feet long, upon either end of which were fastened short j)ieces of 

 rubber hose. These tubes were placed over girdled spots, from which the bark 

 was removed on the thirtieth of May last, and the rubber securely fastened 

 with iron wire to the tree. From all of these specimens a considerable quan- 

 tity of sap escaped, apparently in the form of vapor, and was collected in the 

 tube. There was no layer of wood formed, but the foliage of all except the 

 pine was killed before autumn, apparently by the fermentation of the sap and 

 its re-absorption into the wood. In the case of an elm root, treated in a 

 similar manner, the bark was renewed, probably from the fact that the 

 cambium was in a more advanced state than in the other instances. The root 

 was dug up with care, twenty feet of it drawn through the tube, and then 

 covered again with earth. 



