^ 



r— < A / 



/ \ 



qj ro (U 



o s = 



uQO 



o^- 











Figure 6. Is a por- 

 tion of the trunk of the 

 tree known as sequoia 

 sempirvirens. The larger, 

 open cells grew in the 

 spring, while the smaller 

 and denser cells formed 

 during the summer. Pho- 

 tograph by Professor 

 Harrv P. Brown. 



Figure 7. Photomicrograph 

 of the red blood cells of the fish 

 Amia calva. Each blood cor- 

 puscle remains free to move 

 about and thus do not unite to 

 form tissues as in Figures 5, 6, 

 7, 8 and 9. 



