[163] 



Zhc flDicro0Cope in ipal^ontoIOQ?* 



By Malcolm Poignand, M.D. 



Plate 17. 



THE Palaeontologist, working at the scanty and imperfect 

 remains of the fauna of long past ages found scattered 

 through the deposits of former seas and rivers, with a view 

 of picturing life as it existed in varied conditions through all the 

 vast periods of geological time, has to fill up many a wide gap in 

 the records of the past by his knowledge of the present ; and in 

 doing this, he labours under a double difficulty, namely, that the 

 old remains are often only mere fragments of damaged skeletons 

 of organisms having a most distant resemblance to their nearest 

 modern representatives, and also that all is not by any means 

 known or settled about the new. 



In dealing with a problem so difficult, no fact, however minute, 

 can be neglected ; for it may be a link, however small, in a 

 wonderful and complex chain. Thus, every detail of microscopic 

 structure becomes of real importance and interest, and it is easy 

 to see how the use of the microscope, especially when directed to 

 the examination of transparent sections of rocks and fossils show- 

 ing details of internal structure, has thrown a flood of light on 

 what was dark and obscure before. 



Besides the many fossils, which from their minute size could 

 not otherwise be known at all, whole series of rocks have been 

 found to be mainly composed of organic remains and debris. 



Frequently, the fossil under examination may prove on section 

 only a more or less perfect cast with every detail of internal 

 structure gone, and the cavity occupied by a crystalline or an 

 amorphous mineral mass, so that even the hard shell structure has 

 vanished, and the plant tissue become a mere film of carbon ; all 

 degrees exist between this total loss, and those fossils in which 

 silica, or calcite, has preserved the most delicate structural details 

 without distortion or disarrangement. At times scarcely a change 

 appears to have taken place, for the brown chitin of Scottish car- 

 boniferous scorpions is hardly distinguishable from that of recent 



