568 Microscopical Essays. 



on account of the finenefs of the mefh.es, the hardnefs of the 

 wood, and the famenefs of colour in the conflituent fibres. 



We are here only fpeaking of the lymphatic veflels or lignous 

 fibres of the wood, which exift in it as well as in the bark, 

 though in different ftates ; for the lignous fibres are always harder 

 and lefs flexible than the cortical ones. Malphigi thinks they 

 differ in another particular, namely, that a juice or fluid ifiiies 

 from the cortical, while none is found in thofe of the wood. In 

 this r it would appear from the obfervations of Duharnel, that he 

 was miftaken.. 



A tranfverfe feclion of wood generally appears formed of a 

 number of rays proceeding from the corona to the bark, which 

 are interfered at different diftances by concentric circles, inter- 

 fperfed with veflels of varying, magnitude : the variations in this 

 ftruclure afford much pleafure to the curious obferver, and throw 

 confiderable light upon the nature and properties of timber ; for 

 it is by means of a variety of {trainers that different juices are pre- 

 pared from the fame mafs. Matter, confi dered as matter, has no 

 fhare in the qualities of bodies. It is from the' arrangement of 

 it, or the recipient forms given to it, that we have fo many differ- 

 ent fubflances. According to the modifications that thefe receive, 

 we mall find, the fame light, air, water, and, earth, manifefting 

 themfelves in one by a deadly poifon } and ; in another by the raoft 

 falubrious food. A lemon ingrafted upon an orange flock, is capa- 

 ble of changing the fap of the orange into it's own nature, by a 

 different arrangement of the nutritive juices. One mafs of earth 

 will give life and vigour to- the bitter aloe, to the fweet cane, the 



cool 



