264 



CRYPTOGAMS 



Root hairs seen on young roots are 

 cells of slender tubular shape. Pali- 

 sade cells in the leaf are oblong and 

 contain many chloroplasts or green 

 corpuscles which carry on the work 

 of starch making. The delicate 

 threads of pond scum or spirogyra 

 are made up of short cylindrical cells 

 whose chlorophyll grains are arranged 

 in very beautiful spiral threads. 

 Guard cells of the stomata occur in 

 pairs and are half round or kidney- 

 shaped, and the cells of leaf epidermis 

 are very various in outline. Compare 

 also the sec- 

 tions of mono- 

 cotyl and di- 

 cotyl stems, 



and various other cell forms will be 



seen. 

 But no matter what the form may 



be, all cells studied and most vegetable 



cells will be found to agree in having 



the three parts named wall, proto- 

 plasm, and nucleus. 



Mount thin sections of plant tissues, 



root hairs, pollen grains, moss leaves, 



etc., in water under cover glasses and 



study them with low power ; and when Flo< 1 17. -Diagram of 



the thinness of the section will permit, mesophyl cell of a leaf ; 



examine them also with a higher c ; chIor P last ; n ' m ~ 



cleus ; 13, vacuole ; w, cell 



power. wa ii. 



FIG. 116. Root hair of 

 wheat. 



