300 APPENDIX I. 



the character of the wood alone. The bark might be subject 

 to investigation ; but unfortunately on the specimens placed at 

 the disposal of Prof. Schwendauer the bark is only here and 

 there preserved, and generally in such an imperfect condition 

 that it is difficult to distinguish foreign constituents from the 

 layers of tissue genetically related. However, the Professor 

 gives his opinion with tolerable certainty that the fragments 

 of wood under consideration are derived from the red fir (Abies 

 excelsa}. In this conclusion Professor Schwendauer depends, 

 in the first place, upon the fact that such cells as are porously 

 thick-walled and peridermic, characterizing the red fir, often 

 occur in the peripheral parts of the carbonized crusts, and that 

 in those crusts he has not observed the interlocking, undulating 

 and peridermic elements of the bark of the larch, with its elon- 

 gated prosenchy ma-cells'*, although even these latter might 

 have been expected to occur in stem-organs of corresponding 

 age. Moreover no difference is perceptible between the brown 

 cellular tissue which follows immediately on the above-mentioned 

 porously thick-walled cells and zones of bark, as to the genetic 

 connexion of which with the wood there is no doubt. With this 

 evidence an error in the determination seems to the Professor 

 to be scarcely possible. 



" Judging from the dimensions, and the repeated occurrence 

 of the rods, branches and not stems furnished the materials of 

 these pointed pieces of wood. The number of annual rings 

 varies between five and seven, and their average thickness often 

 does not reach even half a millimetre ('019 inch). At the same 

 time they consist almost entirely of thick- walled cells, or what 

 may be termed autumn wood ; the thin- walled elements are re- 

 duced to about from one to three rows of cells. How far these 

 peculiarities are connected with the climate of the locality, Prof. 

 Schwendauer does not venture to decide, as the extant observa- 

 tions upon the changes of the annual rings in higher latitudes 



* [" The tissue is termed 'prosenchyma ' if the cells are pointed at the 

 ends and much longer than they are broad, and if at the same time their 

 ends penetrate between one another so that no intercellular spaces occur." 

 (< Textbook of Botany,' p. 78, by Prof. Sachs, of the University of Wiirzburg ; 

 translated by A. W. Bennett, M.A., B.Sc., F.L.S., assisted by W. T. Thisel- 

 ton Dyer, M.A., B.Sc., F.L.S. Oxford, 1875.) EDITOR.] 



