*J0 JOL'RXAL 01^ I'OKIvSTRY 



3. The small cells (fibers, etc.) scattered between the pores had 

 thinner walls. 



•I. Dark colored gummy material was apparent (especially near the 

 wound), notably in the rays, often in the liber cavities, and sometimes 

 even in the vessels. 



5. ]\Iuch starch was seen in all the specimens. 



CIIARACTKRISTICS OF TliK GUM DUCTS 



From the material available (collected in December) it was impossi- 

 ble to determine the manner in which the ducts originated and devel- 

 oped. At the end of the season they appeared on the end grain of 

 the wood as openings of various sizes. The ducts first formed were 

 generally largest, being widest in the radial direction and^ oval in con- 

 tour. They usually occupied all the available space between rays. 

 The ducts formed later or at a considerable distance from the wound 

 tended to be smaller and more rounded in form. 



In the girdled tree specimen a single continuous row of ducts above 

 the girdle and a very considerable amount of wood was formed (fig. 1). 

 In the other two specimens more than one row of ducts which varied 

 in size was formed. Some of these ducts exceeded in size the largest 

 in the girdled specimen and others were very small. The size and 

 number of ducts decreased as the distance from the wound increased. 

 Fragments of cells, chiefly from the tangential sides of duct, often 

 extended into the canal cavity. The canals, when examined in longi- 

 tudinal sections, were freciuently somewhat constricted. 



THE DISTRIBUTION OF THE DUCTS 



The girdled specimen showed one uniform row of rather large 

 ducts (fig. 1). The vigorous grov^'th apparent above the girdle was 

 probably made possible by the damming up at this point of the nutri- 

 tive material carried down the tree from the still living and functioning 

 foliage and from the supply of stored materials formed in the sapwood 

 before the girdling. 



In the vertically tapped specimen the rows of ducts extended away 

 on either side of the wound for a distance of about three-quarters to 

 1 inch, where they were gradually reduced and ceased to form. On 

 one side a double row of large ducts was very conspicuous, and a 

 partial third just forming was visible (fig. 2). On the other side only 

 one row similar to that on the girdled tree was noted. 



