20 



GoRHAM; on the Umbellifene. 



very margin of tlie lobes. In order to assure myself that 

 these appearances represented realities, and that the sup- 

 posed veins were real ones, I enclosed the two specimens, the 

 dried one of yEthusa Cyncqiium and the fresh leaf of CEnanthe 

 crocata, to Mr. Jabez Hogg, who submitted them to careful 

 examination under a power of 50 diameters, and kindly en- 

 closed to me a very succinct account of their microscopic ap- 

 pearances, accompanied by a couple of diagrams. The 

 insertion of this memorandum, together with a sketch of the 

 diagrams, will, I am sure, not be offensive to Mr. Hogg. 

 He says, " My rough sketch will show you that I entirely 

 concur in the view you have taken. I submitted the leaf to 

 a power of 50 diameters, which is the best to determine one 

 in the opinion that the venation (iibro-vascular tissue), as it 

 proceeds from the stem, is distributed to the outer portion of, 

 the leaf, and runs on to the summit of the apex, where it 

 unites and conies to a point with its fellow of the other side. 

 At the angles of the leaf the vein bifurcates, and gives off a 

 portion of itself to each side of the leaf, forming a marginal 

 portion of each. 



" In CEnanthe crocata it appears to differ slightly, inas- 

 much as the leaf is thicker, the layer of parenchyma is 

 greater, and the veins appear to enclose a thin layer of the 



Maernified portion of leaf o\ JSthusa 

 Cynapium, sliowiug venation. 



Outer layer of flbro-vascular 

 tissue. Veins. 



colouring matter of the leaf, so that one can see the chloro- 

 phylle between two dark veins ; but here, as in the former 

 case, the veins form a marginal frame, as it were, to the 

 parenchyma. 



