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KIDD'S OWN JOURNAL. 



through the tubes of the alburnum, and that very 

 copiously too. Others would, on the contrary, 

 scarcely exhibit a trace of the fluid in that por- 

 tion of the bole ; but immediately surrounding 

 the pith or medullary canal, an abundant exu- 

 dation would be evident. The cause of these very 

 marked differences were for some time inexpli- 

 cable to me. By following at intervals for several 

 days the tracks of some woodmen, I found that 

 the two appearances, as described, were not 

 observable on stools left from the same day's 

 cutting; or, in other words, where trees were cut 

 yesterday, the sap would perhaps exude wholly 

 from the sap wood; while in those from which 

 they had only been felled a few hours, the tubes im- 

 mediately surrounding the heart of the tree would 

 alone convey the rising fluid. I was confident 

 that these differences did not arise from causes 

 attributable merely to the lapse of time between 

 the felling of the trees and the period of my 

 observation. For, in a series of visits, I found 

 the respective appearances equally evident on the 

 same day of the cutting of the tree. The ap- 

 parent difficulty of solving the problem was now 

 greater than before. This, however, only stimu- 

 lated me in my research. A few hours gave me 

 a clue to the solution. Passing near a hedge-row 

 where the woodmen were at work, I observed 

 them beating the bole of a tree near the base — to 

 facilitate the removal of the bark there, previous 

 to cutting it down. I knew well enough that 

 this process was resorted to when the bark would 

 not " run " well, a contingency brought about by 

 the stagnation of the. sap in that part of the tree. 

 I knew that a change of temperature would in 

 a few hours bring about such a contingency 

 in a tree that previously parted with its bark with 

 facility. Reasoning upon the facts previously 

 gleaned, I returned to the spot shortly, and with- 

 in an hour after the tree had been felled. The 

 workmen were stripping off the bark with dif- 

 ficulty, except at the extremity of the branches, 

 where the difficulty was not so apparent ; and 

 at the upper branches of the tree it parted from 

 the wood readily enough. On examining the 

 stool, I found but a slight trace of sap in the 

 alburnum ; but immediately around, and at a small 

 distance from the centre of the tree, the flow was 

 great. Several other trees cut on the same 

 day presented similar phenomena. The cause of 

 the bark not parting from this tree readily was 

 accounted for by the men, and of course justly — 

 by the frost which on the previous night had 

 been somewhat severe for the season. On the 

 preceding day every tree cut down barked readily 

 enough. Following up the investigation, I found 

 that where the stool of a fallen tree was exuding 

 the sap from the alburnum, the tree had been cut 

 when the weather was favorable, and when the 

 bark from the bole readily separated from the 

 wood ; and, on the other hand, wdiere the vessels 

 around the pith transmitted the fluid, the tree 

 had been felled after a frosty night, or when the 

 weather was cold and ungenial. Having gleaned 

 thus much, I entered into conversation with the 

 men who were cutting the trees. They informed 

 me that when the bark around the lower part of a 

 tree separated with difficulty, it parted much 

 more readily from the branches, especially those 

 near the top, and vice versa. Now from these 



facts, the inferences to be drawn appear to me to 

 be suffieient upon which to build a theory, at 

 once throwing light upon some of the intricacies 

 of the vegetable economy ; and also to afford 

 a beautiful example — one among innumerable 

 others — of the admirable compensative powers so 

 abundantly evident in the mere organic as well as 

 in the more elaborately -organised animal king- 

 dom. The ordinary channel of the upward cur- 

 rent of sap is through the tubes of the alburnum. 

 Its progress is accelerated by warm weather ai.d 

 retarded by cold. If, after the progress of vege- 

 tation in spring has once set in, a retardation in 

 the flow of sap were to accrue in equal ratios with 

 the fluctuations of temperature incident to our 

 variable springs— it is easy to comprehend that 

 utter stagnation in the vital powers of plants 

 would follow — with what results will be readily 

 seen. In a common-sense view of the subject, 

 this contingency is to be apprehended ; but the 

 moment that the conditions favorable for such 

 present themselves, a compensatory power is 

 brought into action, and the demands of the vegeta- 

 ting principle is still supplied. The sap, checked 

 by its near proximity to the lowering temperature 

 of the air, when flowing through the tubes nearest 

 the outside of the tree, immediately seeks other 

 channels open to it ; and thus the circulation goes 

 on unchecked, or at least checked but slightly. 

 These central tubes, a designation given to them 

 by Mr. Knight, are known to extend uninterrup- 

 tedly to the tip of the minutest branch ; and 

 through them a communication is undoubtedly 

 established, either by subordinate vessels or cel- 

 lular tissue, or both, to all parts of the tree. It 

 has always appeared to me that the medullary 

 rays play a more important part in the circulating 

 economy of plants than physiologists have hither- 

 to given them credit for. I am aware tl at 

 the argument I have endeavored to establish 

 is open to apparent objections — and those weighty 

 ones. In hollow trees no central vessels can, at 

 least in the trunk, be present; and these, want- 

 ing the compensating power, cannot be brought 

 into play. And we do not find such remains of 

 trees destroyed by sudden death more frequently 

 than young and vigorous specimens. These 

 are facts that do not admit of argument; yet I do 

 not think they can be justly urged as antagonistic 

 to the position I have advanced. An old and 

 hollow tree, although yearly putting forth its 

 leaves, and possibly producing fruit, merely exists 

 in a morbid state. Its vegetation is feeble; and, 

 as a general rule, year by year it approaches 

 dissolution. Its existence is not healthy ; and, 

 on the same principle that we should not admit 

 the phenomena of life, as exhibited in a deceased 

 animal as natural, we ought" not to allow those 

 which are evident, either as the cause or effect of 

 existence in a decaying tree, as data to assist 

 us in our researches ; except, perhaps, as negative 

 evidence in the healthy economy of other indivi- 

 duals. In the intricate and comparatively little 

 known science of vegetable physiology, inasmuch 

 as it professes to give an insight into the action of 

 the vital principle of plants, every fact, however 

 apparently trivial, must be important. A correct 

 science can only be built up by the accumulation of 

 an infinitive number of isolated facts, contributed at 

 periods, and by individuals widely distant. — G. L. 



