XLIV] CUPRESSINOXYLON 187 



Cupressinoxylon denotes wood similar to Cedroxylon except in the 

 greater abundance of xylem-parenchyma and its occurrence in 

 the spring- as well as in the summer-wood. The medullary rays 

 afford another distinction which according to some authors is more 

 trustworthy than the presence or distribution of the xylem- 

 parenchyma. Gothan 1 , who uses Cupressinoxylon in a more 

 restricted sense, lays stress on the pitting of the medullary cells 

 as a distinctive feature : the pitting is confined to the radial walls, 

 or in other words there is no Abietineous pitting in Cupressinoxylon 

 in the stricter sense. The medullary-ray pits have a broadly 

 elliptical pore which is more or less horizontal at least in the 

 spring-tracheids the Cupressoid type in contrast to the Podo- 

 carpoid type in which in the spring- wood the pore is narrower and 

 more vertical, though in some Podocarps the bordered pits are 

 replaced by large simple pits : in the summer- wood the difference 

 between the Cupressoid and Podocarpoid type disappears. In 

 Cupressinoxylon the medullary rays are uniseriate and not very 

 deep though the depth is a variable character. Lignier 2 states 

 that 60 150 rays occur in 1 square millimetre, another feature 

 of doubtful value. In some species included in Cupressinoxylon 

 the pitting of the tracheids is partly Araucarian as it also is 

 in certain types of Cedroxylon. The presence of Sanio's rims, 

 though not mentioned by many authors, is regarded by Jeffrey 

 and some other American botanists as an important character 

 to be expected in all Coniferous wood other than that of the 

 Araucarineae. It is clear that unusually good preservation is 

 essential for the recognition of such features of the medullary-ray 

 cells as Gothan includes in his definition of the genus ; unless the 

 tissues are well preserved the generic separation of Coniferous 

 types except within very wide limits is impossible. The name 

 Cupressinoxylon may conveniently be restricted to wood having 

 the usual type of tracheal pitting though pits of the Araucarian 

 iype may occur locally, with medullary rays in which the pitting 

 is confined to the radial walls and generally with several fairly 

 small and apparently more or less definitely bordered pits in the 

 field, the pores in the spring- wood being elliptical and more or 

 less horizontal. Kesin-canals absent except in wounded regions 

 1 Gothan (05) p. 39. 2 Lignier (07 2 ) p. 245. 



