146 Mr Nicol 07i the Structure of 



better idea of the respective differences will be had by inspect- 

 ing the figures, ihan can be given in words, but both fall great- 

 ly short of the reality, as seen in the sections themselves, when 

 the eye is aided by a powerful lenp. 



The concentric longitudinal section of the dark part of the 

 wood, presents in the vessels decussating fibres, similar to those 

 occurring in the section parallel to a radius; and both in the 

 dark and pale part of the wood, the partitions of the vessels in 

 the concentric section have expansions or openings similar to 

 each other. 



A difference is also observable in the transverse sections of 

 both parts of this wood. In the pale part, the meshes are con- 

 siderably larger than in the dark part, and the dark part is con- 

 siderably harder and firmer than the pale part. It would be in- 

 teresting to see whether in the large and full grown trees in 

 America, the Taxodiumdisticha presents appearances similar to 

 those above described* That tree being a native of some of the 

 more southern states, is never, as far as I know, imported into 

 this country. It is, therefore, to be hoped, that some of the 

 many scientific gentlemen in America will examine it in both 

 its sides, and favour the world with the result of the investiga- 

 tion. 



If I may judge from the few longitudinal sections I have cut, 

 the Taxus baccata contains discs arranged in single rows only. 

 They are smaller, and even more obscure, than those situated in 

 the dark side of the Taxodium disticha. They scarcely exhibit 

 distinct concentric curves, but this may arise from the difficulty 

 of cutting slices sufficiently thin. As in the other Coniferae, 

 they occur in groups, but the individual discs are always de- 

 tached from each other ; and, as in the other Coniferae, there are 

 many parts of a section where no disc is to be seen. The lon- 

 gitudinal vessels are so very narrow, that the partitions nearly 

 touch one another, at least in certain parts. The partitions con- 

 sist of extremely minute parallel lines,'and in the vessels there are 

 many distinct transverse lines, somewhat resembling those in the 

 dark part of Taxodium disticha. In the yew, however, these lines 

 are placed in a direction nearly perpendicular to the sides of the 

 partitions. They scarcely ever cross one another, and when 

 they do meet, it is only at their extremities, where they give 



