INDIVIDUAL DIFFERENCES 
skill and care to bring before the world the true and 
faithful representations of the nervous, digestive, and 
other organs of the common blow-fly ? Why can this 
humble individual require to be so well furnished with 
these structures, at one time thought to beloug only to 
creatures of a much higher order ? Have we not been 
shown that this little fly has a brain and nervous system 
most complete and perfect in its way ? Has, then, the 
smallest fly this same kind of organization, and which we 
have not yet made microscopes sufficiently perfect to dis- 
cover? Few persons would be able to distinguish one 
flea from another, but the proprietor of the exhibition of 
the “ industrious fleas ” knew each individual perfectly, 
and called them by different names, alleging also that 
the fleas differed much in disposition and temper, a fact 
that those who have had the experience of meeting large 
numbers of them will not doubt. 
207 
