MICRO-ORGANISMS. 765 



Although we do not see these infinitesimal creatures at work, their 

 proceedings are none the less real ; and though their operations are 

 infinitesimal, the aggregate results are vast and in the highest degree 

 important. It may be shown 1. That, as food, they feed a greater 

 number of beings than any other kind of organisms ; 2. That, as 

 scavengers, they eat more refuse than any other group of organisms ; 

 3. That, despite their minuteness, their fossil remains are much greater 

 in bulk and of far more consequence than those of large quadrupeds 

 and serpent-like monsters, such as the mastodon, megatherium, plesio- 

 saurus, ichthyosaurus, etc. ; 4. That, as builders, they have produced 

 immense structures, which far surpass in size all the colossal works of 

 man. The evidence of these statements will be presently given ; but 

 meantime it may be remarked that such grand results redeem the study 

 of microscopical objects from that pettiness which is often imputed 

 to it. 



But not alone because of their stupendous effects are these invisible 

 creatures entitled to our attention. It is in the simplest and smallest 

 creatures that we find the alphabet of the science of life. The rudi- 

 mentary objects of biology are invisible ; and the language of the 

 science could never have been acquired except by first learning its 

 A, B, C with the microscope. It is by the study of the lowest ele- 

 mentary forms of life that we become enabled to comprehend its 

 higher and more complex forms, and we never could have done it 

 otherwise. The anatomy and physiology of our own bodily structures 

 have their roots in the invisible. The grand chain-work of relations 

 that binds all things in order thus loses itself at one extreme in the 

 infinitely great, and at the other in the infinitely small. Embryology, 

 the playground of evolution, shows us microscopic embryos like adult 

 micro-forms as necessary links in the unity of natural phenomena, so 

 that the relationship of living things can only be comprehended by a 

 study of the minutest objects. I do not, however, propose here to 

 enlarge upon this aspect of the subject, but simply to offer a few 

 illustrations of the importance of these micro-organisms. 



Let us first consider the relations of microscopic animals to the 

 crust of the earth, and notice what they have had to do with its forma- 

 tion and constitution. From their low grade of organization they are 

 naturally supposed to have been the earliest creatures on our globe, 

 and there is evidence in favor of this. In ancient geological ages, in 

 whose rocks they are scarce, or hardly to be found at all as fossils, 

 there lived numerous worms, mollusks, etc., which could not have 

 subsisted without them as food. We may conclude, with some degree 

 of certainty, that they were almost as plentiful then as now, probably 

 more so ; but we could not expect these delicate and minute objects 

 to remain preserved until the present, to have withstood the meta- 

 morphoses of the very rocks in which they were imbedded. On this 

 account they are exceedingly rare in the oldest formations, while the 



