EOCKWEED 291 



Does this experiment confirm the result obtained 

 with sulphuric acid ? What effect has Schulze's 

 solution on the outer wall of the cuticular cells ? 

 Draw the section as seen under the low power, show- 

 ing the shape of the branch and the position of the 

 various tissues. Make another drawing of a portion of 

 the section seen under the high power, and showing the 

 structure, etc., of the various cells. Make longitudinal 

 sections of the young branch and compare them with 

 the transverse sections. Draw. 



Examine as above transverse and longitudinal sec- 

 tions of the older branches and of the stem. 



5. The grooving point. — Some of the longitudinal 

 sections of the young branch made above prob- 

 ably pass through the notch at the end of the 

 branch. If not, make such sections, mount in a 

 drop of a mixture of equal parts of glycerine and 

 glacial acetic acid, and examine under the high 

 power. What is the shape of the notch? Of 

 the tips of the branch on each side of the notch ? 

 Note that the notch contains a clear mucilagi- 

 nous substance. Does this entirely fill the de- 

 pression ? Does it extend around on the tips of 

 the branches ? If so, how far ? Of what use 

 may it be ? Note the group of cells, the ixiitial 

 cells, at the bottom of the notch. How are they 

 arranged? What is their relation to the sur- 

 rounding cells ? Notice the large central cell, 

 the initial or apical cell. What is its position 

 with regard to the other initial cells? To the 

 bottom of the notch ? What is its shape ? Size 

 as compared with the neighboring cells? Can 

 you make out the manner in which this cell di- 



