EVIDENCES OF PRIMITIVE LIFE — WALCOTT. 241 



measures of St. Etienne the cellulose membranes showed traces of subjection 

 to butyric fermentation such as is produced at the present day by Bacillus amy- 

 lohacter; he also claimed to have detected the organism itself. Since that time 

 a number of fossil bacteria, mainly from Paleozoic strata, have been de- 

 scribed by Renault, occurring in all kinds of fossilized vegetable and animal 

 debris. The supposed micrococci present little that is characteristic ; the more 

 definite, rodlike form of the bacilli offers a better means of recognition, though 

 far from an infallible one; In a few cases dark granules, suggestive of endo- 

 spores, have been found within the rods. On the whole, the occurrence of 

 bacteria in Paleozoic times, so probable a, priori, may be taken as established, 

 though the attempt to discriminate species among them is pi'obably futile. 



M. Eenaiilt, in 1895, wrote : 



It may be surprising that beings like the bacteria, whose teguments are so 

 slightly distinct, should have been preserved in a manner clear enough so that 

 their presence is often easier to discover when they are fossil than when they 

 are living.* 



The reason for this, M. Renault continues, is because this delicate 

 tegument has taken on a certain discoloration, which makes it stand 

 out clearly from the surrounding matrix. Though, of course, highly 

 microscopic, its form is preserved with absolute perfection. In the 

 secondary and Tertiary (Permian) strata he distinguished several 

 varieties, both of bacteria and micrococci, resembling almost identi- 

 cally the living forms, and he stated that the only reason he hesi- 

 tated to identify them as positively the same was because of the im- 

 possibility of subjecting fossil bacteria to the culture test. In this 

 test, as is well known, the various genera of bacteria, though often 

 looking alike, behave very differently and thus are distinguishable 

 and separable. At present, therefore, Ave may only point out ap- 

 parent generic differences in the fossil bacteria revealed by the 

 microscope. 



PRE-CAMBRIAN ALGONKIAN BACTERIA. 



The presence of minute forms of algse and bacteria in the ancient 

 pre-Cambrian rocks was suspected for several years before they were 

 found. From the part they both play in the deposition of calcium 

 carbonate in modern waters and the fact that bacteria are usually 

 present w^hen animal or vegetable matter is broken down by decom- 

 position it seems that they must have existed almost from the begin- 

 ning of life on earth, and that in this way we may explain the pres- 

 ence of limestone of pre-Cambrian Algonkian time that is found in 

 Montana and other parts of North America. 



In the spring of 1914 after careful study of the problem it was 

 concluded to be quite probable that bacteria were an important fac- 



1 M. Renault, Rechercbes sur les Bacteriac&s fossiles, Ann. Sci. Nat., Bot., Vol. 2, 

 Paris, 1896, pp. 274-349. 



18618°— SM 1915 16 



