336 COMPOSITE ORGANS. CHAP. II. 



Divergent taken, we shall suppose from a piece of Oak or 

 composed Elm, and put under a good glass, it will be found 

 ThreadTof 1 * ^ e c o m P ose d of an assemblage of parallel fibres 

 vesicles. or threads of contiguous vesicles, not forming a net- 

 work, but closely crowded together and compressed 

 into a thin layer, being apparently nothing more 

 than the vesicles or cellular tissue of the pulp that 

 originally existed in the Alburnum, now deprived 

 of its parenchyma, but still filling up the interstices 

 of the concentric layers, and binding them together 

 like a cement. 



To complete the analysis, Senebier macerated, 

 in water and spirits of wine, a slice or layer taken 

 from the trunk of a Fir-tree, and reduced it to a 

 mere skeleton. It presented a net-work of which 

 some of the areas of the meshes were occupied 

 with an intervening substance, and some empty. 

 But the intervening substance remained only 

 where the slice was thick. Where the slice was 

 thin it had disappeared altogether, having been dis- 

 solved in the water or spirits of wine. But it is 

 known that the cellular tissue is soluble in either of 

 these fluids. The conclusion therefore was, that 

 the interstices of the net-work were occupied with 

 cellular tissue, crossing the longitudinal layers in a 

 horizontal direction, and uniting and cementing 

 them together by insinuating itself between them. 



O J O 



But a slice of the transverse section presented 

 also the appearance of a net-work after maceration ; 

 which shows that the concentric layers must be 



