PHENOMENA OF PLANT-LIFE. 33 



and chestnut were selected, which were from two to three 

 inches in diameter. On the thirtieth of May, before any de- 

 position of recently organized tissue was visible, but when the 

 bark was easily separated from the wood, a horizontal incision 

 was made with a sharp knife around each stem, and immedi- 

 ately above this four vertical incisions on the four quarters of 

 the stem about three inches in length. The four strips of 

 bark were then carefully detached from the wood at their lower 

 ends, and a piece of tinned copper, one inch wide, and' long 

 enough to reach around the wood and overlap, was adjusted 

 to the trunk. The bark was then replaced and covered tightly 

 with cloth which had been dipped in melted grafting-wax. The 

 trees grew through the season as usual, and after the fall of the 



o o 



leaves the bandages we e removed and the results observed 



In all cases the new wood was found to have been deposited 

 from the bark and outside of the metallic band. Examina- 

 tion under the microscope showed that a thin layer of paren- 

 chyma, corresponding to the pith of the first year's wood and 

 snch as probably unites all the layers of wood in exogenous 

 steins, was formed upon the metal, and outside of this the 

 fibro-vascular tissue, while the medullary rays were as numer- 

 ous as in the other portions of the layer of wood, and ex- 

 tended directly from the bark to the metal under it, whether 

 examined in a. transverse or a longitudinal section, thus 

 proving that the material did not flow down in an organized 

 condition from above the band. The figures appended will 

 render the entire experiment sufficiently intelligible. (Figs. 

 24-27.) 



This quite satisfactory result demonstrates that the elabo- 

 rated material formed in the leaves descends altogether outside 

 of the wood, and that the inner bark is the most highly vital- 

 ized part of the trunk of a tree and the source of the new 

 layers of wood and bark which are annually produced. 



Much information has also been obtained in regard to the 

 effects of ringing or girdling the trunks and branches of trees 

 by the removal of a band of bark only, or of bark and sap- 

 wood from the entire circumference. 



This has long been practised in new countries to kill the 

 timber which the settler had not time to fell, but must destroy 

 to obtain grain and other crops. 



