DISSECTING OBJECTS. 121 



compound microscope with an erector, page 44 ; or a lens 2 or 

 3 inches focal length, or even smaller, fastened to a stem, so as 

 to be adjustable over the object. 



The following account of Swammerdam's dissections com- 

 mends itself to all microscopists. It is condensed from an 

 extract in Adams's Essays, from Boerhaave's Life of Swam- 

 merdam. 



In the preparation of objects, no man was ever more suc- 

 cessful or more indefatigable than Swammerdam. His chief 

 art seems to have been in constructing very fine scissors, and 

 giving them an extreme sharpness; these he made use of to 

 cut very minute objects, because they dissected them equally, 

 whereas knives and lancets, if ever so fine and sharp, are apt 

 to disorder delicate substances. His knives, lancets, and styles, 

 "were so fine that he could not see to sharpen them without a 

 magnifying glass. 



He was also dexterous in the management of small glass 

 tubes, which were no thicker than a bristle, and drawn to a 

 fine point atone end, but thicker at the other. These he made 

 use of to show and blow up the smallest vessels discoverable 

 by the microscope; to trace, distinguish, and separate their 

 courses and communications, or to inject them with subtile 

 liquors. 



He used to suffocate insects in spirits of wine or turpentine, 

 and likewise preserved them some time in these liquids; by 

 which means he kept the parts from decomposition, and added 

 to them such strength and firmness as rendered the dissections 

 more easy. When he had divided transversely the little 

 creature he intended to examine, and carefully noted every- 

 thing that appeared without further dissection, he then pro- 

 ceeded to extract the viscera in a very cautious and leisurely 

 manner; first taking care to wash away and separate, with 



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