©FSCEIPTION OP THE FIRS. 203 



Firs differ from plants in general io having no «piraVThey h>Te n« 

 vire; for these vessels are absolutely only to be found.****"*' 

 where the leaves require turning, and not when so fastened 

 on the main stem, a$ to be incapable of changing their po- 

 sition: an arrangement that might have been expected, since 

 to turn the leJtes as habit requires, to open uud shut the 

 flower, are the real offices >of the spiral wire. 



The tir tribe differ also in forpaing their bark and rind by Theyalsofon^ 

 leaves; for, while in common plants the juices with the J.!^^^^^^^*^* ^"* 

 thread vessels of the bark form together the upper covering leaves. 

 of the tree, in the lirs they form leaves alone; and with these 

 the tree is covered. The leaves of the pines are more sim- 

 ple in their formation than leavesi having the spiral wire, aU 

 that rolling and pressing is not used .n any of the fir tribe, 

 tiiongh the buds are more difficiiltto be understood ip their 

 general arrangement. To comprehend a leaf bud when 

 forming, you must take it out of the interior of the *' leaf 

 calyx", within which, and next the stem, it will be found. 



The leaf bud consists of several pairs of calyxes, having The leaf l>vii» 

 a'l)undle of leaves weaving: as at tig. 1, Fl. V. Take one 

 of these, and in the solar miscroscope it will show a very 

 curiously worked wood, vessels ready formed ; as a middle 

 to the leaf, and a parcel of threads weaving the sides of 

 the leaf by passing backward and forward : see fig, 2, where 

 a a are the sides, and b b the rpiddle, through which the 

 threads pass. When this is done, the pabulum or blood of 

 the plant coagulates, and settles op the threads, forming a 

 mass both thick aud durable; while the cpbweb skin, which * 

 is woven with the calyxes, fastens on it, and covers the 

 vhole. Now the edges of the leaf begin to shoot, while 

 threads of singular fineness and beauty appear; but scarcely 

 have you time to admire the various prismatic colours they 

 reflect in the sun, ere they are covered by the same cobweb 

 gkin, which raakes^of these apparent glass rings (for such they 

 seem) one regular circular vessel; bordering the leaf, and 

 fastening down the upper surface: the next appearance of 

 the leaves is at the top of a bud, their form is then complete, 

 though extremely small. In this bud you see the first start- 

 ing of the flower bud from the line of life as at fig. 3; where 

 p c are the female buds, d d the leaves. No soouer has the 



flower 



