Organic Remains, Crystals, and Artificial Objects. 93 



proved to be nothing else than a mass of decomposed 

 vegetable matter, the arrangement of its minute in- 

 ternal structure shows that it must have belonged 

 exclusively to the cone-bearing tribe of trees. In 

 some coals, the structure can only be indistinctly dis- 

 cerned ; in others it is very plainly to be recognized ; 

 and it would appear that the Araucaria is the modern 

 plant to which coal makes the nearest approxi- 

 mation. The decomposed wood of which coal 

 consists appears to have "been reduced to a 

 pulpy state by decay, before the process of con- 

 solidation by pressure, aided perhaps by heat, com- 

 menced."* 



And just as these productions of the vegetable 

 world can be referred to their true classes by the 

 microscope's help, so certain fossil spines, bones, and 

 teeth, found in so fragmentary a state that but little 

 of their form could be traced, have been identified by 

 an examination of their minute structure with that in- 

 strument. In a somewhat similar way, the microscope 

 has assisted in throwing light on the past history of 

 the earth's strata. 



The little microscopic vegetables named diatoms, 

 or, at greater length, Diatomacece (to which allusion 

 has already been made), are found living both in fresh 

 and salt water, and their remaius, hardened by the 

 presence of silica, are also to be found in quantities at 

 the bottom of fresh-water lakes, or on the bed of the 

 ocean. When a geologist therefore meets with an 



* Carpenter, p. 752 



