FOSSIL WOOD AND HOW IT IS STUDIED. 95 



in the herbarium would be much more attractive than it is at 

 present. 



It frequently requires considerable ingenuity to properly arrange 

 plants in the press. Those that are less than sixteen inches high are 

 easily managed, and much taller specimens may be bent once, twice 

 or thrice to make them of the right size. There are few herba- 

 ceous plants in the Northern States that cannot be disposed of in 

 this manner. Of others it will suffice if flowers, fruit, all forms of 

 leaves and a section of the stem are preserved. The herbarium will 

 look much better if bulky roots, stems and fruits are pared down on 

 one side, or in some cases on both, before the plant is pressed. Each 

 plant, as it is put into the press, should be arranged as it is to lie on 

 the herbarium sheet. In the case of large plants, one specimen will 

 suffice for a page, but of small ones it is well to press several on the 

 same sheet, taking care that the plants do not overlap one another. 

 It was formerly thought necessary to carefully spread out every leaf as 

 the plants were put in press, but a certain amount of negligence here 

 is rather to be commended, since if all the leaves are so carefully 

 spread, it may be difficult to study the under surfaces of any of them 

 when the specimen is mounted. On this point, therefore, the advice 

 is, Be careful, but not too careful. 



FOSSIL WOOD AND HOW IT IS STUDIED. 

 By F. H. Knowlton. 



FOSSIL or petrified wood, as it is most frequently called, is of very 

 wide distribution, being found more or less abundantly in all 

 geological horizons from the Silurian to the present time, and 

 geographically from almost the furtherest north reached by the 

 Greely expedition to the extreme end of South America, and from 

 Australia, Asia, Africa and the islands of the sea. It may occur as 

 stumps, logs, or even as veritable fossil forests like that of the Yellow- 

 stone National Park, which was described and illustrated in the pages 

 of Plant World for January, 1898. Perhaps most frequently it is 

 found as isolated pieces or logs. 



As far as we now know, the first mention of fossil plants in litera- 

 ture was the description of some petrified wood by Albertus Magnus 

 in the thirteenth century. These earlier writers, however, were more 

 interested in the processes by which fossilization was supposed to take 

 place than in the nature of the objects themselves, and for that matter 

 much popular error still exists as to the kinds of wood found in a fossil 

 state. It is customary for the finders of fossil wood to state with much 

 seeming positiveness the kind of wood in hand. Thus we have pieces 



