The Wonders of Microscopy 313 



fessor Bayliss tersely puts it: "Any object smaller than half the 

 wave-length of the light by which it is illuminated cannot be seen 

 in its true form and size owing to diffraction. Hereby is set a limit 

 to microscopic observation." These are difficult matters, but the 

 important point is that there are practical limits to what the 

 microscope can do in the way of magnification and "resolution." 

 But Mr. J. E. Barnard has recently made an interesting step 

 forward by using an illuminant such as a mercury vapour lamp, 

 which is rich in blue and violet radiations. It may also be prac- 

 ticable to utilise invisible radiations in the ultra-violet, which 

 would further increase the microscope's resolving power. As 

 things are at present, the limit of useful magnification is some- 

 where about 800 diameters. 



Beauty of Microscopic Structure 



We cannot close this article without referring to a very 

 different subject namely, the extraordinary beauty of many 

 microscopic objects. There are endless "beauty feasts" to be 

 found in the architecture of the shells of diatoms, Foraminifera, 

 and Radiolarians ; in the structure of the outside of pollen-grains 

 and butterflies' eggs; in the zoned internal structure of the stems 

 of plants and the spines of sea-urchins ; in the sculpturing of the 

 scales on butterflies' wings and the multitudinous hexagons of 

 their eyes; in the strange hairs on many a leaf and the elegant 

 branching of zoophytes ; in the intricate section of a rock and the 

 variety of snow crystals. Of microscopic beauty there is no end. 



BIBLIOGRAPHY 



CARPENTER, The Microscope (1880). 



DALLINGER, The Microscope (1891). 



EALAND, The Romance of the Microscope (1921). 



GUYER, Animal Micrology (1909). 



LEE, BOLLES, Microtomist's Vade-mecum (7th ed., 1913). 



SCALES, SHILLINOTON, Practical Microscopy (1909). 



SPITTA, Microscopy (1909). 



WRIGHT, ALMROTH, Principles of Microscopy (1906). 



