VIl] FOSSIL BACTERIA. 137 



as a destructive agent in the decay of plant debris in water. 

 He was able to follow the gradual disorganisation of the tissues 

 and the various steps in the ' butyric fermentation ' effected by 

 this Bacterium. Similarly the same author' was able to detect 

 the action of an allied organism in some silicified tissues from 

 the Carboniferous nodules of Grand-Croix, a well-known locality 

 for petrified plants near Saint-:6fcienne. He recognised also the 

 traces of the Bacillus itself in the partially destroyed plant 

 tissues. The Palaeozoic Bacteria made use of some cellulose- 

 dissolving ferment of which the action is clearly demonstrated 

 in sections of silicified tissues. Many of the phenomena 

 described by Renault and Bertrand as due to similar Bacterial 

 action, afford additional evidence that the gradual disorganisation 

 of vegetable tissues was effected in precisely the same manner 

 as at the present day. 



In some cases we have I believe trustworthy examples of 

 the Bacteria themselves, both in coprolites and plant-tissues, 

 but it is more than probable that some of the recorded examples 

 are not of any scientific value. The examination of petrified 

 tissues under the higher powers of a microscope often re- 

 veals the existence of numerous spherical particles and rod- 

 like bodies which agree in shape with Micrococci or Bacilli. 

 Minute crystals of mineral substances may occur in the siliceous 

 or calcareous matrix of a petrified plant which simulate minute 

 organic forms. Vogelsang" in his important work die Krystal- 

 liten has thrown considerable light on the ontogeny of crystals, 

 and the minute globulites and other forms of incipient crystal- 

 lisation might well be mistaken for Bacterial cells. Granting, 

 however, that we have satisfactory evidence, both direct and 

 indirect, that some forms of Bacteria lived in the decaying 

 tissues of Palaeozoic plants, and in the intestines of reptiles 

 and other animals, we cannot safely proceed to specific diagnoses 

 and determinations '- 



' Van Tieghem (79). " Vogelsang (74). Vide also Rutley (92). 



' I am indebted to Prof. Kanthack for calling my attention to an interesting 

 account of Bacilli in small stones found in gall-bladders; a manner of occurrence 

 comparable to that of the fossil forms in petrified tissues. Vide Naunyn (96) 

 p. 51. 



