PART in. RECAPITULATION. 249 



KECAPITULATION. 



NUMEROUS instances of microscopic structure may be 

 found in the vertebrate series of marine animals, but 

 the field is too extensive for the Author to venture 

 upon. 



In the first section of this book, an attempt has been 

 made to give some idea of the present state of mole- 

 cular science far short, indeed, of so extensive a sub- 

 ject; yet it may be sufficient, perhaps, to show the views 

 now entertained with regard to the powers of nature, 

 the atoms of matter, and the general laws resulting 

 from the phenomena of their reciprocal action. By spec- 

 trum analysis it has been shown that not only many 

 terrestrial substances, in a highly attenuated state, are 

 constituents of the luminous atmospheres of the sun 

 and stars, but that the nebulae in the more distant 

 regions of space contain some of the elementary gases 

 of the air we breathe. 



In the succeeding sections it has been proved that 

 the atmosphere teems with the microscopic germs of 

 animal and vegetable beings, waiting till suitable con- 

 ditions enable them to spring into life, and perform 

 their part in the economy of the world. The life his- 

 tory of the lower classes of both kingdoms has been a 

 triumph of microscopic science. 



The molecular structure of vegetables and animals 

 has been investigated by men of science in their mi- 

 nutest details ; the fragment of a tooth, bone, or shell, 



