THE INVISIBLE WORLD REVEALED. 11 



with the highest interest ; since, by a profound investi- 

 gation of the modifications of structure and functions 

 exhibited in these minute organisms, much light has 

 already been shed upon some of the most obscure phe- 

 nomena in the physiology of man. And there are still 

 certain parts of the human frame, whose intimate struc- 

 ture and especial office are unknown, and will probably 

 remain a mystery, unless revealed by observations on 

 these minute forms of being ; in which, from the trans- 

 parency of their integuments, and the distinctness of 

 their internal organs, the most important vital opera- 

 tions are submitted to our scrutiny. 



In contemplating the swarms of living atoms under 

 the microscope, the idea that most strongly impresses 

 the mind, after the first sensation of surprise has sub- 

 sided, is the infinitesimal minuteness, and simple condi- 

 tion of many of the structures, in which that marvellous 

 principle, LIFE^ is enshrined. We have been accustomed 

 to associate the presence of vitality with bodies possessing 

 various complicated organs for the elaboration and main- 

 tenance of the energies of existence ; but here we see 

 perfect and distinct creatures in the condition of single 

 globules and cells, that live, and move, and have their 

 being, and increase in numbers with a rapidity so prodi- 

 gious, and in modes so peculiar, as to startle all our 

 preconceived notions of animal organisation. 



