VIl] BACILLI. 135 



have been minutely diagnosed and figured by Profs. Renault and 

 Bertrand\ These authors have discovered what they believe 

 to be well-defined species of Micrococcus and Bacillus ranging 

 in age from Devonian to Jurassic. The material which has 

 afforded the somewhat startling results of their investigations 

 consists partly of the coprolites of reptiles and fishes, and of 

 silicified and calcified plant tissues. 



Bacillus Permicus. Ren. and Bert.^ (Fig. 28 B.) 



This Bacillus, which was discovered in sections of a Permian 

 coprolite from Central France, has the form of cylindrical rods 

 12 — 14//, in length, and 1'8 — 1*5//, broad, rounded at each end. 

 The rods occur either singly or occasionally, two or three indivi- 

 duals are joined end to end. Fig. 28 B represents a piece of one 

 of Renault and Bertrand's sections ; the small rods are clearly 

 seen lying in various directions in the homogeneous matrix 



/ 



V^ 



B 





Fig. 28. A, Bacillus Tieghemi Ken. and Micrococcus Guignardi Ren. 

 B, Bacillus Permicus Ren. (After Renault.) 



of the coprolite. Each individual is said to be surrounded 

 by an extremely minute empty space '4//, in width, originally 

 occupied by the Bacillus membrane, the central rod representing 

 the mineralized cell-contents. In this example the petrifying 

 substance was probably derived from the phosphate of calcium 



1 Renault (Oo^), (96i), (96-'). 



2 Renault and Bertrand (94). See also Renault (W) p. 8, (96*) p. 449, 

 PI. Lxxxix. (962) p^ 94^ and (963) p. 280, fig. 8. 



