REMARKS ON VEGETABLE PHYSIOLOGY. 



tumn came, the wood was but imperfectly ripened. I left them entirely unprotected, and 

 in the spring the whole of the tops were completely killed, quite down to the ground. The 

 roots, however, all survived, and during the year 1850 they made a tine growth, having 

 thrown up numerous shoots from three to four feet high. I have examined them to-day, 

 and find that the ends of all the branches are killed from one to two feet. We have had a 

 few very cold days during the past winter — yet, on the whole, a rather mild winter tlian 

 otherwise. Again, there was considerable snow on the ground during the most severe 

 weather, and this no doubt protected the trees. From my little experience, and from ob- 

 servation, I am quite of the opinion, that the Osage Orange cannot be relied on for a 

 hedge in a northern latitude. Will others who have had more experience, give us their 

 opinion? 



In conclusion, I would just remark, that in the vicinity of Cincinnati, the Osage Orange 

 succeeds admirably. Such beautiful hedges as I saw there last autumn, are rare indeed, 

 in this country. I fear, however, that for New-York, New-England, Wisconsin, Northern 

 Illinois, &c., it will not answer. Yours verj'- truly, B. Hodge. 



B^iffalo, March 14, 1851. 



Remarks. — We believe we have already given our opinion that the Osage Orange will 

 make a good hedge no farther north than the peach ripens well. But we have no doubt 

 it will answer at Buffalo. It is found by experience, that as soon as the hedge is sheared, 

 and the growth becomes short and well matured, it is far hardier than when the plants 

 are young. Ed. 



SOMEEEMAKKS ON VEGETABLE PHYSIOLOGY. 



BY P. BARRY, ROCHESTER, N. Y. 



In what way arc new layers of wood added to the stems of growing exogenous treesl 



This is a mooted question among vegetable physiologists, and as the subject has been 

 brought forcibly to my mind, by an example which I have met in pruning, I thought it 

 might not be unprofitable to draw attention to this very interesting subject. 



The popular theory, I believe, is that the moisture of the soil enters the roots of plants, 

 through the spongioles or porous points, by absorption — that there it combines with soluble 

 matters already in the roots and stem, and becomes what is called sap — that this ascends 

 through the cells or organs of the stem, into the leaves, where, by parting with water by 

 exhalation, and receiving carbonic acid gas from the atmosphere by absorption, it under- 

 goes certain changes, becomes duly elaborated and fitted for the formation of new parts, 

 when it takes the name of cambium. Then this cambium or elaborated sap, passes down- 

 wards, through the inner bark, and deposites a new la3'er of wood on the top of the pre- 

 vious one, and a new layer of bark loithin the previous one, — and thus what we call the 

 concentric layers or annual rings of wood, by which we count the ages of trees, are formed. 



This, as I have remarked, is the most popular theory, at least so I regard it, of the for- 

 mation of exogenous wood. But there are some learened physiologists and botanists 

 who dissent from this theory. 



Dr. ScHLEiDEN, extraordinary professor of Botany in the University of Jena, in his 

 "Principles of Scientific Botany," a learned and valuable work, says, "this is only a 

 dream picture." " In the first place," says he, " there is no such thing as crude sap. 

 It cannot therefore be carried to the leaves to become assimilated. From whatever part, 



