6 TWINING PLANTS. Cuar. 1. 
were at the same time revolving ; and this was the case 
with most of the plants observed by me. With all, if in 
full health, two internodes revolved; so that by the time 
the lower one ceased to revolve, the one above was in 
full action, with a terminal internode just commencing 
to move. With Hoya carnosa, on the other hand, a 
depending shoot, without any developed leaves, 32 
inches in length, and consisting of seven internodes 
(a minute terminal one, an inch in length, being 
counted), continually, but slowly, swayed from side 
to side in a semicircular course, with the extreme 
internodes making complete revolutions. This sway- 
ing movement was certainly due to the movement of 
the lower internodes, which, however, had not force 
sufficient to swing the whole shoot round the central 
supporting stick. The case of another Asclepiadaceous 
plant, viz., Ceropegia Gardnerit, is worth briefly giving. 
I allowed the top to grow out almost horizontally to 
the length of 31 inches; this now consisted of three 
long internodes, terminated by two short ones. The 
whole revolved in a course opposed to the sun (the 
reverse of that of the Hop), at rates between 5 hrs. 15 m. 
and 6 hrs, 45m. for each revolution. The extreme tip 
thus made a circle of above 5 feet (or 62 inches) in dia- 
meter and 16 feet in circumference, travelling at the 
rate of 32 or 33 inches per hour. The weather being 
hot, the plant was allowed to stand on my study-table ; 
and it was an interesting spectacle to watch the long 
shoot sweeping this grand cricle, night and day, in 
search of some object round which to twine. 
