On, Spurious Appearances in Microscopic Research. 113 



In this case, with the direct light of the condenser, no signs of 

 beading appeared ; a faint shading exquisitely drawn at the upper 

 part suggested structure of some sort in the intercostal spaces. 



Progressing in definition, I now withdrew the antique eighth, 

 and replaced it by the celebrated Powell and Lealand immersion 

 eighth of 1870, and re-adjusting the collar, the appearance, Fig. 3, 

 was displayed, with which Mr. Hollich seemed greatly surprised and 

 delighted, judging from his mute signs and expression of counte- 

 nance. He wrote on paper, he had never seen anything like this 

 before, though he had often drawn the Lepisma. The double bead- 

 ing he readily copied and portrayed the false appearances of 

 Podura-like markings with evident glee. 



The whole of the blank spaces shown between the ribs appeared 

 crowded with a symmetrical arrangement of double beading 

 straightly radiating from direction of the quill. In the drawing 

 the two sets are distinctly shown as darker (ruby colour) and 

 lighter (pale yellow, and sometimes sapphire), whilst these are 

 broken up by the false Podura-like spine displayed in the figure. 



In order to show the true structure of the Lepisma, the 

 dry one-sixteenth was then substituted, and the "A" eye-piece. 



A minute apertured cap was placed upon the condenser, 

 between it and the object. After careful adjustment Mr. Hollich 

 now drew Fig. 4. The spurious spines disappeared. The ribs 

 most brightly, sharply edged with a slightly undulating black 

 border, display the spines shrunken to a slight thickening of the 

 crossings of the darker substratum of beading. 



Compare now these delicate developments of structure with 

 the coarse spurious beading drawn in Fig. 1. Common sense 

 at once revolts against accepting this appearance as even a rough 

 approximation to the truth. Again, the spurious spines of Fig. 3, 

 significantly suggest that those of the Podura, once so generally 

 believed in, are also a delusion. And the delusion is the more 

 pernicious, because it compels the makers to construct their glasses 

 so as to show this delusion in the sharpest form. By many persons 

 the spurious beads seen at the intersecting striae of the Lepisma 

 are considered quite the correct thing. But when once the real 

 structure shown at Fig. 4 is seen by them, their faith in their 

 best glasses begetting these microscopical shams, fades away at 

 once. 



My object in writing these papers, is to induce those observers 

 who rest content with glasses imperfectly constructed to search 

 for a higher standard of definition. The day may arise when 

 a verdict involving human life may depend upon microscopic 

 perfection. I may be excused for saying that I consider that 1 am 

 discharging a duty, as a retired physician, in boldly denouncing 

 spurious appearances when accepted as true. 



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