I62 NATURAL SCIENCE. September. 



Regarding the origin of the resin, it must be noted that it was 

 produced from the various organs of the trees, i.e., from their roots, 

 stems, and branches, and was also formed in different parts of these 

 organs, not only in the wood cylinder, but also in the bark and pith. 

 No doubt the chief production took place in the wood. The normal 

 formation occurred in these just-mentioned channels or ducts, which 

 cross the wood cylinder in a vertical and horizontal direction. 

 Occasionally resin was formed in an abnormal manner, by foreign 

 influences. So, for example, the common resin ducts could become 

 enlarged and multiplied ; moreover, new ones could arise by dissolution 

 of abnormal parenchymatous cells, or of the normal tracheids in any 

 part of the wood. The nature of the cause of these abnormal pro- 

 cesses is so far unknown, but probably they were due to external 

 influences. 



All these masses of resin were formed in the interior of the 

 stems and branches, and would also have remained there if there had 

 been no injury to the bark and wood by which the resin-ducts could 

 become exposed. Certainly those injuries occurred very often in 

 various ways, for at no time has any natural forest existed which 

 contained a single entirely sound and uninjured tree. This natural 

 state of things is now-a-days not so well seen in the well-kept parks 

 of England as in mountain forests of the Continent or of the north, 

 where little or no artificial interference is made by man. If we pay a 

 visit to the virgin forests of the present time, we are able to study at 

 the same time the state of forests of past geological ages, before man 

 appeared. First of all, every tree in life is damaged by the formation 

 of the bark, and this process can be increased by the influence of the 

 atmosphere and heat, by the action of fungi, insects, and other 

 organisms. But much larger quantities of resin will flow out, if the 

 wood itself is injured. This happens naturally to every stem when 

 throwing off its older branches, and, therefore, the knot-holes are to 

 be considered the proper points of outlet of resin. However, there 

 are still more agents at work by which the wounds might be multiplied ; 

 as by the falling down of neighbouring trees during storms or when 

 weakened by old age ; then lightning and other atmospheric influences 

 may deprive a tree of its branches. Sometimes small splinters of wood 

 are enclosed by succinite, and, besides that, a few pieces of succinite 

 present an exterior looking just as if they had caught fire in the forests 

 of those ages. 



The resin within the trees was very liquid, of a light yellow colour, 

 and transparent, but in flowing out it mingled with cell-sap of the 

 damaged tissue, and it acquired a dull appearance and a denser quality. 

 In such a manner drops or irregular larger masses of resin were forced 

 out of the knot-holes and other injured parts of the trees (Fig. i, a). 

 But, afterwards, through the influence of the sun, the enclosed liquids 

 evaporated, and the thick clouded masses of resin became again 

 thinner and clarified. Of English succinite I know some pieces which 



