THE WHITE BAY. 129 



branches. "A plant no less than an animal is symmetrical. Leaves 

 are either single, or else there is a pair or more than a pair 

 upon each joint. When a pair only, they stand always upon ex- 

 actly opposite sides of the stem ; when three, four, or any other 

 number, they divide the circumference of the stem equally, that 

 is, they stand as far apart from each other as possible in the 

 circle. A circle of three or more leaves is called a whorl. The 

 pairs or whorls of leaves follow each other in a fixed order; 

 each pair stands over the intervals of the pair next below, and 

 the leaves of the whorl of three or other number correspond to 

 the intervals of those next below and above. 



" In the alternate arrangement, that is when bud and leaf is 

 produced upon each joint, the single leaves succeed each other 

 in a definite order maintaining a complete symmetry. Each leaf 

 projects from the stem at a fixed angle with that which precedes 

 it, which is uniform for the species, but is different in the dif- 

 ferent species. In the simplest case the second leaf is on exactly 

 the opposite side of the stem from the first, of course higher 

 up ; the third leaf on the opposite side from the second, and 

 therefore vertically over the first. So the leaves are in two verti- 

 cal ranks; the angular divergence, that is, the angle which suc- 

 cessive leaves make is one half the circumference of the stem. 



"Other plants have the angular divergence one-third, that is, the 

 second leaf is placed one-third round the stem ; the third is one- 

 third round from that, and the fourth of course comes directly 

 over the first, the fifth over the second, and so on, the leaves 

 being hence disposed in three vertical ranks." Alders and sedges 

 form an example of this. "A line traced on the stem through 

 the place of attachment of the successive leaves forms a spiral : 



