Electron Microscopy ,^97 



slipped under the emulsion and lifted otit carryino the emulsion with 

 it. To hold the emulsion in place without slipping it is folded under 

 three sides of the slide, dried in place and the exposure made. (Bogo- 

 roch, 1931; Pelc, 1956; and Simmel, 1957) 



(b) Dipping in fluid emulsion: 



This is simpler than the above method. Mounted sections protected 

 by a celloidin coat are dipped in a liquid emulsion, dried and left in 

 the exposure box for the proper tiine. (Messier and Leblon, 1957 ; and 

 Joftes, 1959) 



comments: 



In either [a) or (b) method, the film is developed, fixed, and cov- 

 ered or sprayed with Krylon. 



At all times when working with photographic emulsions darkroom 

 safety measures must be observed [Wratten Safelight #2). 



Staining: 



Sections used for autographs can be stained. Pelc (1956) has used 

 celestin blue and hematoxylin, neutral red and carbol fuchsin, hema- 

 toxylin and eosin, carmalum, Giemsa, toluidine blue, and methyl 

 green-pyronin. Some workers find stains confusing because the emul- 

 sion gelatine absorbs them. Sinimel et al. (1951) used metanil yellow 

 and hematoxylin with clearer results. Feulgen staining can be used. 

 (Also see Merei and Gallyas, 1960) 



Most autoradiographs should be protected by glycerol jelly mount- 

 ing, Krylon spraying or dehydration, clearing and moimting in a 

 resin. 



General Reference: Fitzgerald et al. (1953) 



Electron Microscopy 



Among the methods in use for investigators in biological and medical 

 fields, one of the newest and fastest growing is electron microscopy. By 

 1940 several electron microscopes had been developed in different parts 

 of the world. Knoel and Riiska in Germany had a practical marketable 

 research scope by 1939. England began work in 1936 and RCA in the 

 United States started to develop one in 1938, and had one on the market 

 in 1941. RCA also has developed a desk model. In the last few years the 

 means of cutting sections do^vn to 1/20 micron have become reliable. 



The electron microscope has a higher resolving power than the light 



