THE NERVOUS CYTOLOGY OF PERIPLANETA ORIENTALIS. 357 



EXPLANATION OP PLATES XXV-XXVIIL 



All figures represent nevous elements, usually cell-bodies, from the thoracic ganglia of the common cockroach, 

 Periplaneta orientalis. The different colors of the stains used are not represented because the relative appearances 

 of the cells, etc., can be better compared in monochrome. 



PLATE XXV. 



Fig. 1. Vom Rath preparation. Section of a cell at right angles to its chief axis. X1000. 



Figs. 2, 3. Vom Rath preparations. Longitudinal sections of two different cells, showing the distribution of the 



fibrillse from the nerve-fibre. X1000. 

 Figs. 4, 5. Vom Rath preparations. Two sections of a cell showing whorls of fibres. XlOOO. 

 Fig. 6. Vom Rath preparation. A part of a cell-body with a favorable view of the cytoreticulum and the 



granulations. X 1300. 

 Figs. 7, 8, 9, 10. Vom Rath preparations. Transverse and longitudinal sections of nerve-fibres showing different 



degrees of damage due to the methods of fixation. XlOOO. 

 Figs. 11, 12. Picroformalin preparations (Nissl and eosin stains). Cells showing the two zones, the varying sizes 



of the meshes of the reticulum, and the varying amounts of deeply staining substance. XlOOO. 

 Fig. 13. Picroformalin preparations (Nissl and eosin stains). Two adjacent cells containing different amounts of 



deeply staining substance. X1400. 



PLATE XXVI. 



Fig. 14. Picroformalin preparation (Nissl and eosin stains). Tangential section at the junction of the two zones. 

 X4000. 



Fig. 15. Lang preparation (Nissl and eosin stains), showing a greater laceration of the outer zone than after picro- 

 formalin. X1100. 



Fig. 16. Chromoxalic preparation (Nissl and eosin stains), showing considerable matting of fibrillae; takes dye 

 reluctantly. XlOOO. 



Figs. 17, 18. Absolute alcohol preparations (polychrome stain). Nuclear membrane ruptured; cytoplasm crowded 

 into a perinuclear ring. XlOOO. 



Fig. 19. A portion of the cell-body near the nucleus of the preparation from which Figure 17 was drawn. X4000. 



Fig. 20. Fresh preparation. In this and in other fresh preparations the outline and portions of the network were 

 rapidly sketched with the camera and the drawings finished with other fresh cells under the microscope 

 for reference. X1300. 



Fig. 21. Fresh preparation. X500. 



PLATE XXVII. 



Figs. 22, 23. Fresh preparations. X700. 



Fig. 24. Fresh preparation. Camera drawing of a part of the cytoplasmic reticulum. X700. 



Fig. 25. Outline of a fresh preparation of the only bipolar cell seen. X 1300. 



Fig. 26. Fresh preparation showing the origin of a nerve-fibre. The individual fibrillse are coarser than they actually 



appeared. X 1300. 

 Fig. 27. Teased preparation fixed in formalin vapor (polychrome stain) and showing the apex of the cell and a 



nerve-fibre. XlOOO. 

 Fig. 28. Enlarged view of the fibre shown in Figure 27. X4000. 

 Fig. 29. Fresh preparation after treatment with Lang's solution. XlOOO. 

 Fig. 30. Vapor of formalin preparation (polychrome stain). X900. 



Fig. 31. Part of the cytoplasm of the preparation from which Figure 30 was drawn. X3500. 

 Fig. 32. Vapor of formalin preparation (polychrome stain). X900. 

 Fig. 33. Part of the cytoplasm of the preparation from which Figure 32 was drawn. X3500. 



