Foreword to Part I 



The preparation of objects for micro- 

 scopic examination — more colloquially 

 known as "making microscope slides" — 

 has a twofold purpose. On the one hand it 

 may be desired to preserve in permanent 

 form objects too small or too dehcate to be 

 handled by the ordinary methods of mu- 

 seum preparation. Second, and far more 

 important, it may be necessary to make 

 permanent preparations of objects and 

 tissues in such a manner that their struc- 

 ture may be more clearly seen under the 

 microscope. In both cases, the object is 

 mounted on a slide, which is nowadays a 

 standardized 3" XI" strip of thin glass. 



Originally microscope slides were very 

 different and were usually made by taking 

 a sHp of ivory, about 2" X }i", and drill- 

 ing through it a hole of about %" in diam- 

 eter. This hole was then enlarged from 

 each side, about a third of the way 

 through, to a }'i" diameter, thus leaving a 

 ridge of ivory in the center. The depres- 

 sion on each side of the slide was fitted 

 ^^ith a ring of spring steel and several disks 

 of mica of a half-inch diameter were fur- 

 nished with each sUde. To make a mount, 

 a piece of mica was inserted from one side 

 and held in place by the slip ring, the ob- 

 ject was placed on it and another disk of 

 mica was then inserted from the other side 

 and, in its turn, held in by a slip ring. This 

 was the only type of shde available until 

 about the middle of the 18th century when 

 glass shdes first made their appearance. 

 These glass slides were, however, of very 

 little use, with their talc covers which re- 

 mained the greatest bar to the progress of 

 microtomy. 



Toward the close of the first half of the 

 19th century Messrs. Chance, Birming- 

 ham, England discovered how to make 

 thin glass coverslips. They were for many 

 years (Queckett 1855, 287) the only manu- 

 facturers, and until the discovery of oil 



immersion objectives microscopists were 

 entirely dependent upon the increasing 

 thinness with which these glasses could be 

 supplied. Microscopists were still seeking 

 for magnification rather than resolution, 

 and by 1880 (Beale 1880, 351) a coversHp 

 had been made sufficiently thin to permit 

 the use of a ^^o-inch "high dry" objec- 

 tive. Coverslips are now taken so much for 

 granted that the contribution made to the 

 development of biology through the intro- 

 duction of thin glass is often overlooked. 

 The earliest method of using these thin 

 coverslips with glass shdes was by holding 

 the cover in place with the aid of a paper 

 label which covered all the slide except the 

 area immediately over the object. These 

 labels were often fancifully engraved to 

 the design of the individual technician and 

 an excellent and well-illustrated descrip- 

 tion of their use is to be found in Martin 

 1872, pp. 46-52. 



Microscope mounts, as made today, 

 consist of three types. These are, first, 

 wholemounts, in which organisms or pieces 

 of organisms are mounted under a cover- 

 slip on a slide; second, smear -preparations, 

 in which either a cut surface or a viscous 

 fluid is smeared on a shde to form a thin 

 layer which is subsequently preserved 

 under a cover glass; third, sections, in 

 which thin shces of objects are mounted 

 under a coverslip. Where objects are cut 

 into a series of sections, each of which is 

 mounted in consecutive order on a slide, 

 the preparation is known as a serial 

 section. 



The simplest slide to prepare is that in 

 which the object is mounted dry. An ex- 

 ample of this is shown in Fig. 1 where a 

 series of diatoms have been spread on a 

 slide, and a covershp placed over 'them. 

 This coversHp is held in place by a ring of 

 cement which is prevented from running 

 under the edges of the covershp by some 



