Cuap. II. TROP^OLUM. 61 



as thin as fine twine. One such shoot revolved in a 

 course opposed to the sun, at an average rate, judging 

 from three revolutions, of 1 hr. 23 m. ; but no doubt 

 the direction of the revolving movement is variable. 

 When the plants have grown tall and are branched, 

 all the many lateral shoots revolve. The stem, whilst 

 young, twines regularly round a thin vertical stick, 

 and in one case I counted eight spiral turns in the 

 same direction ; but when grown older, the stem often 

 runs straight up for a space, and, being arrested by 

 the clasping petioles, makes one or two spires in a 

 reversed direction. Until the plant grows to a height 

 of two or three feet, requiring about a month from the 

 time when the first shoot appears above ground, no 

 true leaves are produced, but, in their place, filaments 

 coloured like the stem. The extremities of these 

 filaments are pointed, a little flattened, and furrowed 

 on the upper surface. They never become developed 

 into leaves. As the plant grows in height new fila- 

 ments are produced with slightly enlarged tips ; then 

 others, bearing on each side of the enlarged medial tip 

 a rudimentary segment of a leaf ; soon other segments 

 appear, and at last a perfect leaf is formed, with seven 

 deep segments. So that on the same plant we may see 

 every step, from tendril-like clasping filaments to perfect 

 leaves with clasping petioles. After the plant has grown 

 to a considerable height, and is secured to its support 

 by the petioles of the true leaves, the clasping fila- 

 ments on the lower part of the stem wither and drop 

 off; so that they perform only a temporary service. 



