128 



Plant Tissue Culture 



Pig. 40. Bow root cultures are measured. The flask containing 

 the culture is held in the Lef1 hand. The righl hand holds a flexible 

 celluloid rule which is placed under the flask and is bent to a curva 

 ture approximating that of the root. With the zero poinl under the 

 base of the root, ;i very accurate estimate can be made of the root's 

 length. In expert hands the error of such measurements "will seldom 

 exceed 3 or l per cenl of the true length. 



