NO. 4 NERVOUS SYSTEM OF A CENTIPEDE — LORENZO II 



ends in gold chloride and one minute in oxalic acid produced optimum 

 results. Cresyl violet (0.25-percent aqueous) was used as a counter- 

 stain after toning for demonstrating the neuronal cytoplasm. The 

 microtechnical schedules found most effective are given as follows : 



Paraffin method. 



1. Kill and fix in modified Bouin's no longer than 12 hours, no less 



than 8. Decapitate and remove antennae, tips of poison claws. 



2. Wash in several changes of 50-percent ethanol for i hour. 



3. Dehydrate in ethanol/n-butyl series, combined as follows : 



Ethanol n-butyl 



(a) 25 ml. of 50 percent 4 ml. li hr. 



(b) 20 ml. of 70 percent 6 ml. i hr. 



(c) 17 ml. of 80 percent 9 ml. 2 hrs. 



(d) II ml. of 95 percent 14 ml. 2i hrs. 



(e) 6 ml. of 95 percent 19 ml. 6 hrs. (2 changes) 



(f) 25 ml. 6 hrs. (no longer) 



4. Complete dehydration and clearing in terpineol, at least over- 



night. (Several days are not injurious.) 



5. Infiltrate with paraffin-bayberry wax (9:1) in oven at 59°C- 



about five changes, or until the odor of lilac disappears, in the 

 course of about 6 hours. (Material left longer does not 

 harden appreciably.) 



6. Block in paper boats, orient specimen quickly and cool ; harden 



in cooled water. 



7. Block is trimmed, squared after being affixed to wooden carrier, 



and sectioned at 10 micra. 



8. Serial sections placed on clean slides, flooded with albumenized 



water, and placed on warming table (47°C.). Ribbons are 

 stretched only if necessary. 



9. Drain off excess fluid (much of the picric acid will be removed 



from tissue at this stage!) ; reorient ribbons ; chill slide under 

 dry ice for about a minute and blot gently, face down, on filter 

 paper. 



10. Continue drying on warming table; complete in desiccator for 



several hours before deparaffinizing. 



11. To eliminate section loss, place slides in o.i -percent celloidin in 



ether-alcohol (1:1) for 5 minutes after the second alcohol 

 rinse in the deparaffinizing series. 



12. Remove slides from celloidin solution, drain, and dry in air no 



longer than i minute ; continue hydration as usual, omitting 

 95 percent alcohol. 



