98 CIRCUMNUTATIXG MOVEMENTS OF CHAP. II. 



some cause thickened in several instances apparently 

 in correlation with the fleshy nature of the mature 

 plant so as to contain a store of nutriment sufficient 

 for the seedling, and then that one or both cotyledons, 

 from being superfluous, decreased in size. It is not 

 surprising that .one cotyledon alone should sometimes 

 have been thus affected, for with certain plants, for 

 instance the cabbage, the cotyledons are at first of 

 unequal size, owing apparently to the manner in which 

 they are packed within the seQd. It does not, how- 

 ever, follow from the above connection, that whenever 

 a bulb is formed at an early age, one or both coty- 

 ledons will necessarily become superfluous, and conse- 

 quently more or less rudimentary. Finally, these 

 cases offer a good illustration of the principle of com- 

 pensation or balancement of growth, or, as Goethe 

 expresses it, " in order to spend on one side, Nature 

 is forced to economise on the other side." 



Circumnutation and other movements of Hypocotyls' 

 and Epicotyls, whilst still arched and buried beneath 

 the ground, and whilst breaking through it. According 

 to the position in which a seed may chance to 

 have been buried, the arched hypocotyl or epicotyl 

 will begin to protrude in a horizontal, a more or 

 less inclined, or in a vertical plane. Except when 

 already standing vertically upwards, both legs of the 

 arch are acted on from the earliest period by apo- 

 geotropism. Consequently they both bend upwards, 

 until the arch becomes vertical. During the whole of 

 this process, even before the arch has broken through 

 the ground, it is continually trying to circumnutate 

 to a slight extent ; as it likewise does if it happens at 

 first to stand vertically up, all which cases have 

 been observed and described, more or less fully, in 

 the last chapter. After the arch has grown to some 



