40 SAVAGE SUKVIVALS 



There are about a million species of animals 

 known to science at the present time, that is, there 

 are about a million that are known and named. 

 And there are probably a million more that are 

 not yet catalogued. And it is estimated that from 

 20 to 100 times as many species of animals have 

 lived and perished entirely from the earth as to- 

 day survive — 20 to 100 times as many species^ re- 

 member, not individuals. The rock masses over 

 which we walk every day are vast cemeteries in 

 which lie all that is left of immeasurable billions 

 who once lived, breathed, and had their existence 

 as we do now. These facts give a little idea of 

 the nature and extent of the struggle which has 

 gone on here on the earth, and whose story lies 

 locked forever in the fossil-bearing rocks. 



2. Vestigial Organs. 



Vestigial means ** remnant," or *Hrace;'' and 

 vestigial organs means ** remnant organs," or- 

 gans which have gone out of use and which are in 

 the act of passing away as a result. 



In the struggle for life species are continually 

 displacing each other, continually driving each 

 other out of one set of surroundings into another 

 set. When a species is driven out of one set of 

 surroundings to which it is fitted into another set 

 different from the first, it is very likely to have 

 some organs that are left over and not needed in 

 the new environment. On the other hand, it will 

 probably need some organs which it does not have. 



