Apeil 17, 1896.] 



SCIENCE. 



583 



Easin, of Baltimore, who placed his com- 

 modious tug at Mr. Bibbins' disposal for the 

 investigation. 



A number of small pieces of amber were 

 found in situ in thin strata composed largely 

 of comminuted lignite. By careful exca- 

 vation Mr. Bibbins was able to expose a log 

 of lignite which showed in several cases 

 the amber in its interstices. Through the 

 kindness of Mr. Bibbins I have been enabled 

 to investigate the structure of this amber- 

 producing tree. 



This log was found about 20 feet below 

 the surface in strata provisionally regarded 

 by Mr. Bibbins as of upper Potomac (upper 

 part of Lower Cretaceous) age. About 4 

 feet in length of the log was taken out. It 

 was very soft when excavated and hardly 

 to be distinguished from the surrounding 

 matrix. When dried by exposure to the 

 air it becomes thoroughly disintegrated into 

 minute fragments, and even when treated 

 by hardening substances still retains so 

 much iron pyrites that it appears impossible 

 to stop its reduction to powder. Before fossi- 

 lization the log had been completely honey- 

 combed, apparently by a Teredo-like mol- 

 lusk. This condition made its compression 

 easy, and when excavated it was found to 

 be much flattened. It was about 14 inches 

 in long, and 6 inches in short diameter. 



When observed with the naked eye or 

 with a low-power lens the wood appears to 

 be admirably preserved. The grain shows 

 very clearly and, when it is split radially, 

 faint traces of the medullary rays can be 

 made out. It is very soft and may be 

 sliced with an ordinary razor without treat- 

 ment of any kind. But when studied un- 

 der a compound microscope it is found at 

 once that miich disintegration and distor- 

 tion has taken place. The wood cells have 

 been flattened and crushed until it is quite 

 impossible to make out their character. 

 Figure 1, magnified 320 diameters, repre- 

 sents the lumen of the cells. It is impos- 



70(7 



© 



sible to make out their outline or to deter- 

 mine whether or not there were rings of 

 growth. 



The radial section appears the best pre- 

 served of all. An exceptionally well pre- 

 served portion is shown in figure 2. It 

 shows the cell walls to be thick, and also 

 that the radial walls are provided with a 

 single series of large pits. The outlines of 

 the outer and inner circles are so obscure 

 that it is not possible to make satisfactory 

 measurements. (In the drawing they of 

 course appear distinct, but they are only 

 approximate.) The medullary rays should 

 be observed in longitudinal section, but 

 they can not be made out with sufiicient 

 distinctness to be drawn with the camera. 

 The usual number appears to be four, but 

 it may vary from two or three to as many 

 as seven. 



The tangential section, of which a frag- 

 ment is given in figure 3, shows the extent 



to which the medullary rays have been 

 compressed. The opposite walls are pressed 



