Propagation by Division. 183 



d Seeds should be planted no deeper than is necessary to 

 insure the proper degree of moisture; otherwise the plantlet 

 expends a needless amount of energy in reaching the 

 surface (51, 48). Very small seeds should be only slightly 

 covered, if at all, and must receive artificial watering 

 when necessary (52). Spores must not be covered with 

 soil at all (53). 



B PROPAGATION BY DIVISION. 



345. We have seen that a part of a plant, placed under 

 favorable conditions, is usually capable of developing into 

 a complete plant (340). A section or cutting of the stem, 

 for example, that has no roots at the time it is cut off, 

 may be caused to form roots, and thus become a complete 

 plant. A cutting of a root may also put forth a bud, 

 which in turn may develop into a shoot, and form leaves, 

 flowers and fruit. Again, we have seen that portions of 

 cambium from different, nearly -related plants may unite 

 by growth (70), which enables us to change undesirable 

 sorts into valuable ones by grafting (383). These and 

 certain other methods of multiplying plants, come under 

 propagation by division. 



In propagation by division , the presence of at least one 

 healthy growing point (67) in the part selected for the propa- 

 gation is generally essential to success and is always helpful. 



The processes treated in this and the two succeeding 

 sections may be likened to surgical operations in medi- 

 cine. If plants are less highly organized and possess less 

 of sensibility than the higher animals, they are, none the 

 less, living beings. Violent operations, if necessary, should 

 always be performed with this truth in mind. Needless 



