PART II. 



HISTOLOGY AND PHYSIOLOGY. 



THE CELL. 



94. If a thin, transverse section of a stem or leaf be 

 examined under the microscope, it will be found to consist 



of a multitude of globular or 

 more or less elongated and 

 flattened bodice, called cells 

 (Fig. 167). These vary in 

 shape in different plants, or 

 even in different parts of the 

 same plant. They may be 

 globular, as in many unicel- 

 lular plants, pollen grains, 

 etc. (Fig. 168) ; they are pyriform, or pear-shaped, in case 

 of some swarm spores (Fig. 169) ; they are many-sided, 

 or elongated, in tissue of ordinary plants ; they may take 



on a very irregular shape, as stellate (Lat. stella, star), in 

 the tissue of the Hush (Fig. 170) ; or ramose (Lat. ramus. 



Fig. 1G7, Section of stem of CleTttaiis. Fig, 1G8. Pollen grain of Morning-Glory. 

 Fig. 1G9. Swarm spores. Fig. 170. Stellate cells from the stem of Rush i^yuncut), 



(.72) 



