NO. 4 NERVOUS SYSTEM OF A CENTIPEDE — LORENZO I3 



Hydroquinone i .o gm. 



Sodium sulfite 5.0 gm. 



Distilled water loo.o ml. 



6. Rinse slides (2-4 changes) in distilled water several minutes. 



7. Gold tone immediately as follows : 



(a) i.o-percent gold chloride {without acetic acid), 15 



seconds. 



(b) Rinse briefly in distilled water, several dips. 



(c) 0.25-percent oxalic acid, 60 seconds. 



(d) Rinse in distilled water, about 30 seconds. 



(e) 5-percent thiosulfate, 5 minutes. 



(The gold chloride may be used repeatedly for 

 about 100 slides ; the oxalic acid and sodium thio- 

 sulfate solutions should be made up fresh before 

 use.) 



8. Wash thoroughly in at least 12 changes of distilled water over 



a period of i hour. 



9. Counterstain in 0.25-percent aqueous cresyl violet (Coleman 



and Bell Co.) for 6 minutes at 57 °C. (Just before use add 

 15 ml. of 1 0-percent acetic acid to every 90 ml. of solution, 

 heat gently and filter.) 

 10. Rinse in several changes of distilled water, dehydrate rapidly, 

 clear in xylol, and mount. 



RECONSTRUCTION TECHNIQUES 



During the preparation of the microscopic material care was taken 

 to avoid distortion of the internal structures. Efforts were made to 

 orient the tissue blocks so that nearly perfect transverse, longitudinal, 

 and horizontal sections were obtained. A dissecting microscope was 

 often employed to orient the centipede heads in melted parafiin, since 

 the cephalic capsule is about i mm. in length. 



Photography of the stained sections greatly facilitated a study of 

 each serial section and aided in the interpretation of relationships. All 

 photographs were taken with a single lens reflex, 35-mm. Exakta 

 camera and a compound microscope with apochromatic objectives. An 

 illuminator with a ribbon filament, 6-volt tungsten lamp was employed. 

 A green filter was used to increase contrast in the silver preparations. 

 Panatomic-X film developed in FR X-22 was used, and enlargements 

 were printed on F-4 Kodabromide paper developed in Kodak Dektol 

 (1:2). 



