553.29 i6i 



I. 



On Engiish Amber and Amber generally. 



II. 



HAVING discussed the properties of succinite, and obtained a know- 

 ledge of its geological occurrence and distribution, it would be of 

 interest to inquire into the plants from which it was produced some- 

 where near the beginning of the Tertiary period. It has already been 

 mentioned that succinite is to be found together with rounded carbonised 

 pieces of wood, but of course, these disconnected pieces need not 

 have produced it. Only such specimens as are enclosed by the 

 fossil resin belong with certainty to the succiniferous trees. Con- 

 cerning the method of examining these woods, one was formerly 

 content to get some splinters of them by cutting with a knife, and 

 this was the way in which H. R. Goeppert, who made some very 

 creditable investigations of succinite, proceeded. But these prepara- 

 tions are not sufficient for investigating the finer microscopical 

 structure, wherefore I have made use of the method of examining 

 petrified woods by microscope-sections that was invented sixty-five 

 years ago in England : for William Nicol first prepared microscope- 

 slides and H. T. Witham published the method in his " Observations on 

 Fossil Vegetables," London, 1831. Thus I have obtained such correct 

 and large sections of the wood that they could be figured in my 

 monograph of the Baltic amber trees. ^ 



In general, the preservation of the wood and bark is good, some- 

 times very good, because nature itself has encased the pieces in the 

 liquid resin, just as we put up sections of recent plants in Canada 

 balsam. Therefore, all the details of the structure are often as well 

 seen as in living plants. The wood is formed of tracheids, which are 

 arranged in distinct rings of growth, representing probably annual 

 rings. The walls of the tracheids, especially the radial walls, are 

 furnished with one to three vertical rows of bordered pits. Moreover, 

 there are vertical resin ducts, surrounded by parenchymatous cells 

 and horizontal medullary rays, which also often enclose a resin duct ; 

 the middle of the wood is filled by the medullary cylinder or pith. 



1 " Monographic der Baltischen Bernsteinbiiume, &c." Mit iS lithogr, Tafeln in 

 Farbendruck. Danzig, 1890. 



