128 GEOLOGICAL CHANGE, AND TIME. 



ami (leprejssioii. So fiagiiientary are tliey in f>onic regions that we can 

 easily (lemonstrate tlie leiigtli of time represented there by vstill exist- 

 ing sedimentary strata to be a astly less tliaii the time indicated by the 

 gaps in the series. 



There is yet a further and impressive body of evidence furnished by 

 the successive races of plants and animals which have lived upon the 

 earth and have left their remains sealed up within its rocky crust. No 

 one now believes in the exploded doctrine that successive creations and 

 universal destructions of organic life are chronicled in the stratitied 

 roclvs. It is everywhere admitted that, from the remotest times up to 

 the present day, there has been an onward march of development, type 

 succeeding type in one long continuous progression. As to the rate of 

 this evolution x>i'eeise data are wanting. There is however the im- 

 portant negative argument furnished by the absence of evidence of 

 recognizable speciiic variations of organic forms since man began to 

 observe and record. We know that within human experience a few 

 species have become extinct, but there is no conclusive proof that a 

 single new species have come into existence, nor are appreciable 

 variations readily apparent in forms that live in a wild state. The 

 seeds and j^lants found with Egyptian mummies, and the flowers and 

 fruits depicted on Egyptian tombs, are easily identitied with the vege- 

 tation of modern Egypt. The embalmed bodies of animals found in 

 that country show no sensible divergence from the structure or propor- 

 tions of the same animals at the ])resenr day. The human races ot 

 Northern Africa and Western Asia were already as distinct when i»or- 

 trayed by the ancient Egy])tian artists as they are now, and they do 

 not seem to have undergone any perceptible change since then. Thus 

 a lajise of four or live thousand years has not been accomi)anied by any 

 recognizable variation in such forms of plant and animal life as can be 

 tendered in evidence. Absence of sensible change in these instances 

 is, of course, no proof that considerable alteration may not have been 

 accomplished in other forms more exposed to vicissitudes of climate 

 and other external intiuences. But it furnishes at least a presumption 

 in tinor of the extremely tardy progress of organic variation. 



If however we extend our vision beyond the narrow range of human 

 history, and look at the remains of the plants and animals ])reservedin 

 those younger formations which, though recent when regarded as parts 

 of the whole geological record, must be many thousands of years older 

 than the very oldest of human monuments, we encounter the most im- 

 pi-essive proofs of the persistence of specific forms. Shells which lived 

 in our seas before the coming of the Ice age present the very same 

 peculiarities of form, structure, and ornament which their descendants 

 still ])ossess. The lapse of so enormous an interval of time has not 

 sufliced seriously to modify tliem. So too with the plants and the 

 higher animals which still survive. Some forms have become extinct, 

 )>ut few or none Avhich remain display any transitional gradations into 



