The Extent of Root Surface 



61 



rapidly as it was needed. In reflecting upon the extent of root 

 surface indicated by the photo -engraving, let it be remembered 

 that no root -hairs contribute to the mass of the bundle, and that 

 only a part of the roots proper are there, for many of the smaller 

 fibers were unavoidably broken off during the operation of wash- 

 ing away the soil. 



Referring, now, to Fig. 11, it will be seen how completely the 





Fig. 11. Distribution of corn roots in field soil. (From "The Soil.") 



whole soil of the field is threaded with roots ; for in both cases 

 two hills of corn, standing opposite each other in adjacent rows, 

 are shown, and the roots meet and pass one another between the 

 hills, and in the younger stage these had already exceeded a 

 depth of two feet ; while in the second case, taken just as the 

 corn was coming into tassel, the roots had descended until at 

 this time the whole upper three feet of the field soil was so fully 



