THE MICROSCOPE 



55 



]DD 



D 



PLATE 27. Common Errors in Sketching. 



1. The cell walls of these parenchyma cells should be continuous and should 

 be brought back to the starting point. 2. The cells in this fragment of tissue 

 should be surrounded by a cell wall of definite thickness and the space between the 

 cells is much exaggerated. 3. The parts of this aggregate crystal (rosette type) are 

 sharp pointed and not rounded as illustrated. 4. The sides of this crystal should 

 be straight lines as acicular crystals are never curved. 5. These cork cells are too 

 symmetrical in form. There are slight differences between individual cells and these 

 are not represented. 6. Parenchyma cells never appear as exact geometrical forms. 



