246 Canadian Record of Science. 



ably well preserved. A very marked peculiarity of the 

 specimen is to be found in the extreme lightness and the 

 porous nature of the greater part of the structure. This 

 latter feature is so conspicuous as to render the coarse cel- 

 lular tissue readily distinguishable without the aid of a glass. 

 As determined by Sir Wm. Dawson, the infiltrated material 

 is wholly calcite, and it is probable that the deposition was 

 limited, being developed first in the cell walls and later ex- 

 tending to some of the cell cavities which in small tracts are 

 completely filled up. 



The various sections examined show the entire structure 

 to be in a fine state of preservation. From them we gather 

 the following facts : — 



The parenchyma tissue is very coarse and thick walled. 

 It abounds in intercellular spaces which are, for the most 

 part, small. The primary cell is usually well defined, but 

 no structural markings have been observed. (Plate I, fig. 3.) 



The bundles of the marginal zone are radially elongated, 

 usually two or three times larger than broad and narrower 

 at the inner extremity. Occasionally they are double as 

 shown in fig. 1, from which it will also be seen that the cell 

 walls are very thick, and there is an apparent absence of 

 vessels. The outer face of t v : ~ figure also shows a portion 

 of the bundle removed. This is a common feature, although 

 in some cases the same space is occupied by cells which 

 appear isolated — separated by somewhat wide structureless 

 areas, a result evidently due to the decay of the primary 

 cell membranes and a wide separation of the liberated 

 parts. We may, therefore, refer the disappearance of the 

 cortical structure and the outer portions of the marginal 

 bundles to the action of decay, rather than to the operation 

 of mechanical action on the stem. Viewed longitudinally 

 these bundles also show a complete absence of vessels, while 

 the cells are found to be very long with tapering extremi- 

 ties, similar in many respects to the cells of bast tissue. No 

 markings have been detected. 



The bundles of the inner vascular zone exhibit consider- 

 able variety of form, and most of them show interior tracts 



