286 KANSAS UNIVERSITY SCIENCE BULLETIN. 



The bark was removed from a straight shoot and the wood 

 was covered with wax. One end was fitted with a glass funnel, 

 and the other end was passed through a rubber cork into a side 

 delivery flask almost full of water, the end of the shoot ex- 

 tending below the surface of the water. The air was then 

 exhausted from the flask by means of a filter pump, and the 

 shoot was shortened until bubbles of air streamed from the 

 lower end. Mercury was then poured into the funnel and the 

 shoot was shortened a little at a time until a spray of tiny 

 drops of mercury began to fall from the lower end of the shoot, 

 showing that some of the tracheal tubes extended the entire 

 length of the shoot. The shoot used was four years old at one 

 end and five years old at the other. 



In tangential section there are about three medullary rays 

 to the square millimeter. These rays vary in width from one 

 to twelve cells, or from .034 to .216 mm., and in vertical length 

 from nine to one hundred forty cells, or from .15 mm. to 2.42 

 mm. The cells of the rays are plain pitted and have an aver- 

 age width vertically and tangentially of .03 mm., and vary 

 in length from .013 mm. to .1 mm. 



A longitudinal section was made through the region of the 

 stem where the old wood joined the new wood (fig. 58). The 

 xylem of the old wood was so perfectly connected with that of 

 the new wood that no distinct line of division could be made 

 out. However, there were shorter tracheids at the close of a 

 year's growth, and there was a difference between the old and 

 the new pith, the new pith being made up of larger cells and 

 containing less stored food (fig. 59). 



CHEMICAL TESTS ON CELL CONTENTS. 



The Leaf. 



Leaves that had been in bright sunlight for several hours 

 brought in and tested at once for starch with iodine showed 

 the presence of much starch. 



Sections of the same leaves boiled with Fehling's solution 

 showed great numbers of crystals of cuprous oxide, especially 

 in the palisade cells. 



Sections of leaves in alcannin over night showed no oil. 

 Sections of leaves in Sudan III over night showed no oil, ex- 

 cept here and there in the epidermis. 



Sections of leaves were treated with methylene blue as a 



