"^^="■1 KNOWLEDGE OF THE MIDDLE AGES. 389 



centuries had the discussion of petrifactions in general been raging and 

 the discovery of petrified wood only added new complications to an old 

 controversy. Enlarging upon Aristotle's doctrine of spontaneous gen- 

 eration, the scholastic writers had afBrmed that it was as possible for- 

 stones of any required form to produce themselves as for living animals 

 and plants. Avicenna in the tenth qentury had proposed his vis la/pi- 

 difica, and Albertus Magnus in the thirteenth his virtus formativa. 

 Bauhin^' predicated a spirit of the Universe, or Archseus, while Liba- 

 vius ^^ held that fossils sprang, like living things, from a true germ or 

 seed. Balthasar Klein obtained a specimen, one side of which was 

 stone, the other coal, and this excited intense curiosity. He sent the 

 specimen to Matthiolus, who studied it and came to the conclusion" 

 that coal was the third or final step in the process of transmutation, 

 and that just as wood turned into stone so stone in turn was transformed 

 into coal. Klein's owa views were much more rational. The discovery 

 in the mines of Joachimsthal of a petrified trunk with the bark on 

 added to the interest already aroused on this subject and kept alive the 

 discussion. 



Thus far only petrified wood had been observed or considered, and 

 although Johannes Kentmann,*^ in 1565, had given an account of some 

 ieaf impressions formed by incrustations of tufa, no mention of the re- 

 mains of the foliar organs of plants in any true rock formation seems to 

 have been made until 1664, when Johann Daniel Major published at Jena 

 his "Lithologia curiosa, sive de animalibus et plautis in lapides versis." 

 This work was so little known that whatever its merits it attracted no 

 notice, and the subject of fossil plants in the sense now commonly under- 

 stood remained practically untouched until the close of the seventeenth, 

 century. 



In 1699 appeared at London Lhwyd's " Lithophylacii britannici Ich- 

 nographia," *' in which were not only described but figured with suf- 

 ficient fidelity for identification a number of ferns from the coal meas- 

 ures of England. A period of great activity in this department of hu- 

 man observation, we can scarcely say science, followed the appearance 

 of this work, but before attempting to follow the development from 

 this point we may pause a moment to consider the history and progress 

 of ideas which in all ages so largely formed the spur to observation and 

 investigation. 



With the discovery of fossilized leaves and fronds by Major and 

 Lhwyd all the departments of paleontology had been opened to dis 

 cussion, and in those early days discussion was the primary consid- 



^ De fontibus et balneis Bollensis. 



* Hist, et invest, font, medic, ad Tubarin sub Rotembergo. P. Ill, Franc, ad Mrenum. 



oiEpiatolae ad Baahin, III, pp. 141, 142, 1564. 



fBNomenclatura rerum fosslliura, etc. Tit. vi, Lapides. Tiguri, 1565, fol. 38. 



|» Eduardi Luidii Lithophylacii britannici ichnographia, sive lapidum aliorumque 

 fossilium britannicorum singnlari figura insigninm * • * distributio classica. 

 Londini et Lipsise, 1699. 8°. (See Tab. 4 & 5, Figs. 184», 186, 188, 189, 190, 191, 197; 

 see, also, two Annalarias, Figs. 201 & 202, Tab. 5.) 



