THE MINUTE. 



sisting in their material, their shapes, and their 

 sculpturing. 



."». Their spontaneous movements, and the 

 mystery which hangs over the manner in which 

 these are performed, a mystery which all the per- 

 severance of hundreds of the best microscopists 

 has not yet been able to dissipate. 



(>. The power which their structure possesses of 

 taking up the siliceous matter held in solution in 

 the waters, and forming of it solid flint,— a process 

 which excites our wonder and which is quite be- 

 yond our comprehension. 



7. The uncertainty which attends our conclu- 

 sions as to their true character. Are they ani- 

 mals? Are they plants? The question is still be- 

 fore the judges. Ehrenberg and other names of 

 high eminence have set them down as animals, 

 but the preponderance of modern opinion is in 

 favour of their vegetable nature. And there are 

 some who would fain make of them a fourth king- 

 dom, neither animal, nor vegetable, nor mineral, 

 but an independent group possessing affinities 

 with all. 



S. Their minute dimensions. The actual size 

 varies exceedingly, according to the species, be- 

 tween one-fiftieth, and one six-thousandth of an 

 inch, or even wider limits. Perhaps, however, we 

 may set down as an average size for an oblong 

 frustule, a length of one-thousandth of an inch, 

 and a width of one-five-thousandth ; that is. that 

 if you could make a chain of them, set end to end, 

 in contact, it would take a thousand specimens to 

 measure an inch, while, if you made a row of 

 them, side by side, five thousand would be re- 

 quired to fill the same extent. 



Highly attractive to a young observer is the 

 variety of life which meets his eye, as he examines, 

 153 



