lOG MB. DAEWIN ON CLIMBING PLANTS. 



helix), Ficus repens, and F. barhatus, have no power of movement, 

 not even from the light to the dark. As previously stated, the 

 Soya camosa (Asclepiadacese) is a spiral twiner, and can likewise 

 adhere by rootlets even to a flat wall ; the tendril-bearing Big- 

 noma Tuoeedyana emits roots, which curve half round and adhere 

 to thin sticks. The Tecoma radicans (Bignoniacese), which is 

 closely allied to many spontaneously revolving species, climbs by 

 rootlets J but its young shoots apparently move about rather more 

 than can be accounted for by the varying action of the light. 



I have not closely observed .many root-climbers, but can give 

 one curious little fact. Ficus re^ens climbs up walls just like Ivy; 

 when the young rootlets were made to press lightly on slips of 

 glass, they emitted (and I observed this several times), after about 

 a week's interval, minute drops of clear fluid, not in the least 

 milky like that exuded from a wound. This fluid was slightly viscid, 

 but could not be drawn out into threads ; it had the remarkable 

 property of not drying. One drop, about the size of half a pin's 

 head, I slightly spread out, and scattered on it some minute 

 grains of sand. The slip of glass was left exposed in a drawer 

 during hot and dry weather, and, if the fluid had been water, it 

 would certainly have dried in one or two minutes ; but it remained 

 fluid, closely surrounding each grain of sand, during 128 days: 

 how much longer it would have remained I cannot say. Some 

 other rootlets were left in contact with the glass for about ten 

 days or a fortnight, and the drops of fluid secreted by them were 

 rather larger, and so viscid that they could be drawn out into 

 threads. Some other rootlets were left in contact during twenty- 

 three days, and these were firmly cemented to the glass. Hence 

 we may conclude that the rootlets first secrete a slightly viscid 

 fluid, and that they subsequently absorb (for we have seen that it 

 will not dry by itself) the watery parts, and ultimately leave a 

 cement. When the rootlets were torn from the glass, atoms of 

 yellowish matter were left on it, which were partly dissolved 

 by a drop of bisulphide of carbon; and this extremely volatile 

 fluid was rendered, by what it had dissolved, very much lesS' 

 volatile. 



As the bisulphide of carbon has so strong a power of softening* 

 indurated caoutchouc*, I soaked in it during a short time many 



Mr. Spiller has recently shown (Chemical Society, Feb. 16, 1865), in a 

 paper on the oxidation of india-rubber, that this substance, when exposed to 

 the air in a fine state of division, gradually becomes converted into brittle, 

 resinous matter, very similar to shell-lac. 



