Fig. 

 Fig. 

 Fig. 



5. Brain of Campodea from above. X 75. 



6. Thoracic ganglion of Campodea from above. X 75. 



7. Region of last two thoracic ganglia above and some of the abdominal 

 ganglia in the lower part of the figure, from Campodea, showing the 

 lateral tracheal tubes. X 75. 



8. One of the abdominal ganglia of Campodea showing tracheal tubes. X 75. 



9. One of the thoracic ganglia of Campodea showing tracheal tubes. X 75. 



10. Tracheal distribution in the subesophageal and first thoracic ganglion 

 of Evalljapax. X 50. 



11. Tracheal distribution in the last two ganglia of Evalljapax. X 50. 



12. Brain of Lepisma showing where the deeper masses of cells are as seen 

 from a methylene-blue preparg,tion. X 20. 



Fig. 13. Part of the brain of Lepisma from below showing areas of most abundant 

 cells. X 20. 



14. Subesophageal ganglion of Lepisma showing distribution of trachea. 



15. Third thoracic and first abdominal ganglia of Lepisma showing tracheal 

 distribution. X 20. 



16. Last two abdominal ganglia of Lepisma with tracheal distribution. X 20. 

 , 17 and 18. Abdominal ganglia of Machilis, showing medial nerve. X 22. 

 19. Brain of Evalljapax from above showing distribution of thickest masses 



of cells on the left side and the distribution of tracheal vessels on the 

 right side. X 50. 

 , 20 and 21. Supra- and subesophageal ganglia of evalljapax as shown in 

 longitudinal section. X 50. 



Fig. 

 Fig. 

 Fig. 



Fig. 

 Fig. 



Fig. 

 Fig. 



Fig. 

 Figs 

 Fig. 



Figs 



