120 DESCRIPTIVE CATALOGUE 



Medullary rays are conspicuous, even the uniseriate rays 

 being noticeable in transverse section (PI. VIII, fig. 2, m.); they 

 measure 30-40 p in tangential diameter, and radially corre- 

 spond to 2-4 tracheids. In radial section some of the elements 

 are rectangular, and some narrow down at each end to a spindle- 

 shaped form (see text-fig. 29). Many of the elements, both 

 bordering and interspersed through the ray, are true ray- 

 tracheids with small, round, bordered pits (text-fig. 29, rt.). The 

 distinction between these and the other ray-elements is not 

 very sharp, and there are all gradations between small round 

 pits and the large open slits with a very narrow border (PI. IX, 

 fig. 3, jp.w., and text-fig. 29, 2>' m *)- Some of the elements with 

 the larger pits have maescs of dark brown granular contents, as 

 is seen in text-fig. 2i) and in the dark horizontal bands in 

 PL IX, fig. 3. The ray -tracheids bordering the ray show but 

 slight irregularity of outline, and do not appear to have any of 

 the denticulate thickenings characteristic of the hard Pines. 

 Owing to the fine granular deposit which masks the walls 

 of most of the elements, it is difficult to make quite reliable 

 observations on the point, but there do seem to be true, though 

 small, " abietinean pittings " on the end-walls of the ray- 

 elements. In tangential section some of the end-walls can be 

 clearly seen to be perforated with small oval and circular pits. 



AFFINITIES. Whether or not the resin-canals in this form are 

 traumatic instead of normal is a point which cannot be deter- 

 mined from the given material. The specimen is a wedge of 

 wood measuring only 1-5 x 3'5 cms. in diameter, so that if the 

 wound had been serious it is not beyond the realm of possibility 

 that the whole of this area should have been under its influence 

 and thus forced into the production of traumatic resin-canals. 

 On the other hand, this would be rather an unusually large 

 area to be so uniformly affected by a wound of which there is 

 no sign in the section. It must be noted that the rows of 

 resin-canals are fairly uniformly distributed all through the 

 wood in rather regularly diffused, alternating, tangential bands 

 (PI. VIII, fig. 2). Furthermore, the canals, on the whole, do 

 not have the characteristic of running together tangentially, 

 which is noted by Jeffrey (1905) as one of the features to be 

 seen in traumatic resin-canals. As Jeffrey observes, an actual 

 wound is not the only stimulus which will produce traumatic 



