AS TO OURSELVES 



jumped to their feet in fright, not sure 

 but he might start to unscrew his head 

 next, for had any of their venerated an- 

 cestors ever seen such an uncanny per- 

 formance with teeth? They afterwards 

 solemnly said that never would they have 

 believed this if they had not seen it. 



There is the essence of incredulity the 

 world over, for a common English saying 

 is, Only seeing is believing ; in other words, 

 we are to believe most in the reports of 

 that sense which is more uniformly mis- 

 taken than in any other. The scientist, and 

 particularly the biologist, is not sure about 

 what he sees until he has otherwise tested 

 it. Thus thirty-three distinct varieties of 

 streptococci have been identified so far, 

 and though in appearance they look ex- 

 actly alike, it will make considerable dif- 

 ference to a man which one of them hap- 

 pens to get into him. Likewise all metazoa 

 begin each as a micrococcus, and they then 

 183 



