FORMS OF LIVING-MATTER UNITS 103 



into one or other of the 230 known crystalline 

 types. As G. H. Lewes aptly said: * " The link 

 which unites all organisms is not always the com- 

 mon bond of heritage, but the uniformity of 

 organic laws acting under uniform conditions." 



We may, therefore, well recognise that the lower 

 the forms of life the nearer they are to their 

 source the greater is likely to have been the 

 similarity among those that have been produced 

 in different ages, just as the lowest forms are now 

 practically similar in all regions of the earth. 

 How otherwise, consistently with the doctrine of 

 evolution, are we to account for the fact that dif- 

 ferent kinds of Bacilli and Micrococci have been 

 found in animal and vegetal remains in the Trias- 

 sic and Permian strata, in Carboniferous lime- 

 stone, and even as low as the Upper Devonian 

 strata ? 2 Is it conceivable that with mere lineal 

 descent such variable living things could retain 

 the same primitive forms through all these chang- 

 ing ages? Is it not far simpler and more pro- 

 bable to suppose, especially in the light of the 

 experimental evidence now adduced, that instead 



1 Fortnightly Review, April, 1868 ; article on " Mr. Darwin's 

 Hypotheses," p. 373. 



2 See Ann. des Sciences Nat. (Bot.), 1896, ii., pp. 275-349. 



