208 Canadian Record of Science. 
all stages of disintegration. Sometimes the centre is a mere 
structureless mass, when the surface is perfectly preserved ; 
Sometimes it is the surface that is disorganised. In 
other cases portions are well preserved, and others disin- 
tegrated in the most capricious manner. I have specimens 
of fossil coniferous wood in which portions are disintegrated 
along the medullary rays, giving the appearance of widely 
separated wedges, and others in which concentric bands are 
alternately preserved and destroyed, others in which 
irregular spaces have been eaten out and filled with struc- 
tureless matter, and others in which crystalline or con- 
cretionary structures have been developed in spots, giving 
the most grotesque and inexplicable appearances. Yet in 
all these cases we have the general form ofa trunk and 
portions of it in which the structures are preserved. 
In one example of silicified wood I have found regularly 
formed prisms of quartz deposited in rows along the woody 
fibres as if these had formed original parts of the structure. 
In fossil woods it is also very common to find the tissues 
compressed, folded and contorted in spots, so as to give the 
most unnatural possible appearances. Now in all such 
cases it is surely reasonable to take the well—preserved 
portion as the means of interpreting the rest, though I have 
known cases where, for want of attention to this, portions 
of woody tissue have been described as cellular, in con- 
sequence of their being disintegrated by the crystallization 
of quartz. 
It is also to be observed that there is a gradation in the 
probability of the preservation of structures. A very finely 
tubulated structure, like that which is supposed to have 
constituted the proper wall of Kozoon, is rarely perfectly 
preserved. In modern foraminifera infiltrated with 
glauconite, we usually see their finer structures pre- 
served only in spots, ora part of the length of the tubes 
only filled. The larger cells are often infiltrated when 
the tubuli are empty. A coarse canal system is more 
likely to be perfectly infiltrated. Further, in Tertiary Num- 
- maulites the fine tubes are often filled with calcite, while the 
