266 GENERAL ANA TOMY OR HIS TOLOG Y OF BLO W-FL \ '. 



regarding it as a direct modification of the cell substance, and 

 not as an excretion formed in the cell and poured out on its 

 surface. I shall hereafter recur to this point. 



The Nucleus. The appearances presented by nuclei are much 

 more diverse than those exhibited by cells. The nucleus 

 exists in two conditions the resting stage, which is charac- 

 teristic of a cell which is not undergoing division, and the 

 active nucleus, in the dividing cell. 



The Resting Nucleus in insects is generally enclosed in a 

 thin capsule, and consists of a clear plasma, nucleoplasm, in 

 which a reticulum, or long coil of fibre, is seen; this fibre is 

 termed the nuclear fibre or nuclear skein. It consists of 

 granules, chromatin granules so called from their affinity for 

 such dyes as logwood or carmine, nuclear stains, when properly 

 applied (see Appendix to Chap. IV.). The chromatin granules 

 are united by a substance which does not stain achromatin. 



DESCRIPTION OF PLATE XVI. 



Cells and Nuclei, exhibiting their principal modifications. 



FlG. I. A large epithelial cell from the hypoderm of the larva, with strialed cell 



substance, a vacuolated nucleus, and a nuclear nucleolus. 

 FIG. 2. Two hypodermal cells from the larva in the resting stage. 

 FlG. 3. Multinucleate pericardial cells from the young nymph, possibly young fat 



cells. 

 FIG. 4. An amceboid cell from the blood of the young imago, loaded with droplets 



of oil. 



FIG. 5. An amceboid cell from the blood of the young imago. 

 FlG. 6. An amoeboid corpuscle from the same, enclosing a vacuolated nucleus. 

 FIG. 7. A similar cell with a single droplet of oil in its interior. 

 FIG. 8. The cell-capsule of an exhausted fat cell from an adult egg-laying female, 



showing stellate daughter cells. 

 FIG. 9. A young fat cell from the imago. 



FIG. 10.- The nucleus of a fat cell from the nymph filled with leucocytes. 

 FIG. ii. An epithelial cell from the hypodermis of a larva, showing the intra- 



cellular reticular spongioplasm ; the nucleus enclosing a nuclear nucleolus. 

 FlG. 12. The nucleus of a salivary cell from the larva, showing the nuclear thread. 



FlG. I2a. A portion of the nuclear (chromatin) thread, showing the chromatin 



beads. 



FIG. 13. Goblet cells from the proximal intestine of the imago. 

 FlG. 14. Secretory epithelial cells, from the proximal intestine of the imago. 

 FIG. 15. Rodded salivary cells from the sericterial glands of the imago. 

 FIG. 16. Epithelial cell from the distal intestine of the imago, with a striated 



border. 

 FIG. 17. Large cell from the rectal papilla. 



