SEEING BY AID OF THE LENS 



299 



into slices so that they will be transpar- 

 ent or at least thin enough to allow the 

 light to pass through them. 



To make slices of such hard bodies 

 demands a good deal of skill on the part 

 of the microscopist. The spine is first 

 cut with a hue, sharp saw into sections 

 as thin as possible and these slices are 

 then carefully and gently rubbed on a 

 finely grained whetstone until they are 

 thin enough for microscopical examina- 

 tion. This must be done with great care 

 or the hard and rather brittle -pieces will 

 he broken and the workman will lose 

 his labor for the section will then be 

 spoiled for any satisfactory study. 



Fig's. I and 2 show sections of two 



FIG. 1. TRANSVERSE SECTION OF 

 ECHINUS SPINE. 



spines from two different species of sea 

 urchins. Both are greatly magnified 

 and both are pleasing in appearance by 

 reason of the regularity of the parts. 

 The inside parts of many things made by 

 nature are more interesting and attrac- 

 tive than the outside. It is so in the case 

 of the sea urchin's spines. Outwardly 

 they are apparently only solid, nearly 

 smooth rods of stone, but when the mi- 

 croscopist has prepared them for his fav- 

 orite instrument they reveal unsuspected 

 beauties and unsuspected points of in- 

 terest and of instruction. 



In Fig. 3, five similar sections are 

 arranged in a group for comparison. The 

 four outer objects that resemble little 



FIG. 2. SECTION OF ECHINUS SPINE 

 FROM ANOTHER SPECTES. 



cogwheels are placed there only to orna- 

 ment and complete the picture. They 

 are not sections of the urchin's spines. 



BE A IT Y OF THE COMMONPLACE. 



After all, the great lesson is that no 

 special natural sights, not Alps, Niagara, 

 Yosemite, or anything else, is more 

 grand or more beautiful than the ordin- 

 ary sunrise and sunset, earth and sky, 

 the common trees and grass. — Walt 

 \\ hitman. 



FIG. 3. GROUPED SPECIMENS OF ECHI- 

 NUS SPINES. 



