OBJECTS rOR THE MICROSCOPE. 33l 



the instances which occur of such imitations; and I shall only remark 

 that, generally speaking, these arms and instruments in structure and 

 finishing far exceed those which they resemhle." 



METHOD OF DISSECTING INSECTS. 



Swammerdam excelled in the preparation of insects. Neither difii- 

 oultj' nor disappointment could make him abandon the pursuit of any 

 object until he had obtained a satisfactory idea of it. But, unhappily, 

 few of the methods he used in preparing his objects for the micro- 

 scope are now known. Boerhaave examined with the strictest atten- 

 tion all the letters and manuscripts of Swammerdanr which he could 

 find; but his researches were far from being successful. Ihe follow- 

 ing are all the particulars which have come to the knowledge of the 

 public. 



For dissecting small insects Swammerdam had a brass table, to 

 which were afiixed two brass arms moveable at pleasure to any part of 

 it. The upper part of these vertical arms was constructed in such a 

 manner as to have a slow vertical motion; by which means the ope- 

 rator could readilv alter the height as he saw convenient. One of 

 these arms was to hold the minute objects, and the other to apply the 

 microscope. -^i^ 



The lenses of Swammerdam's microscopes were of various sizes as' 

 well as foci; but all of them the best that could l)e procured both for 

 the transparency of the glass and the fineness of the workmanship. 

 His obsen'ations were alwavs beo;un with the smallest magnifiers, from 

 which he proceeded to the greatest; but in the use of them he was so 

 exceedingly dexterous, that he made every observation subservient to 

 that which succeeded it, and all of them to the confirmation of each 

 other and to the completing of the description. His chief art seems 

 to have been in constructing scissars of an exqui^ite fineness, and 

 making them very sharp. Thus he was enabled to cut very minute 

 objects to much more advantage than could be done by knives and 

 lancets; for these, though ever so sharp and fine, are apt to disorder 

 delicate substances by displacing some of the filaments and drawing 

 them after them as they pass thro vigh the bodies; but the scissars cut 

 them all equally. The knives, lancet-, and styles he made use of in his 

 dissections, were so fine that he could not see to sharpen them without 

 the assistance of a magnifying glass ; but with these he could dissect 

 the intestines of bees with the same accuracy that the best anatomists 

 can do those of large animals. He made use also of very small glass 

 tubes, no thicker than a bristle, and drawn to a very fine jx)int at one 

 end but thicker at the other. These were for the purpose of l>lowing 



