204 LETTER XLVI. 



towards the circumference, you will find from sixteen 

 to twenty more of these appearances (E. f.). They 

 are caused by vour having- cut throun^h the ends of 

 highly elastic cords, consisting of spiral vessels (b. & 

 c), strengthened by a quantity of woody fibre (_/.), 

 and surrounded on all sides by tough, thick-sided 

 cells ; respiration goes on through the spiral vessels, 

 circulation through the woody tubes, which also give 

 strength and elasticity to the cords, and digestion 

 through the surrounding cells. Moreover, near the 

 circumference of the tendril (E. a.) these cords are 

 repeated on a smaller scale, spiral vessels being placed 

 in the centre, thick-sided cells on the outside, and a 

 few tough, woody tubes immediately in contact mth 

 the spiral vessels ; the object of these is no doubt to 

 strengthen the tendi'il still further, and to do away 

 with all possibility of the cords near the centre being 

 accidentally broken. 



Thus you see nature provides not fewer than sixty 

 or seventy cords or muscles, each of a most wonderful 

 degree of completeness, to give its requisite strength 

 to a tendril, the diameter of which does not exceed 

 the twelfth part of an inch. I am sure you will now 

 agree with me, that however admirable the contri- 

 vances are, which readily meet the eye in the vegetable 

 kingdom, there is something still more wonderful in 

 the hidden and microscopic machinery, by which their 

 organs are set in action. 



