LIST OF ILLUSTRATIONS 



FIGURE PAGE 



1. Various spheroidal cells ........ 1 



2. Ameba proteus in motion ....... 3 



3. Paramecium caudatum .... ... 4 



4. A generalized cell ......... 5 



5. A unicellular flagellate animal (Tetramitus chilomonas) . . 6 

 6. Egg of a clam (Cumingia tellinoides) . . 7 



7. Primary spermatocyte of a turtle (Cistudo Carolina) 

 8. Spermatid of opossum in early stage of metamorphosis into a sper- 

 mium ....... 



9. Cells from the newly-hatched rainbow trout, treated according to 

 Meves' technic for the demonstration of mitochondria (plasto- 

 somes) ........ .9 



10. Two cells from the mesenchyma of the newly-hatched rainbow trout 9 

 11. Intracellular network, or ' trophospongium ' within a Purkinje cell 



of the cerebellum of Strix flammea . . 10 



12. Diagram illustrating the various theories of protoplasmic structure 11 

 13. Egg of the blood starfish (Henricia sanguinolenta) in later growth 



period ...... 11 



14. Pancreas cell of turtle, filled with zymogenic granules . . 12 



15. Motor nerve cell from the ventral horn of the spinal cord of the ox 12 

 16. Interstitial cell from the testis of a twenty-one year old man. 



Showing granular and filamentous mitochondria . . 13 



17. A neuron (giant pjo-amidal cell, or cell of Betz) from the cerebral 



cortex of man, showing the neurofibrils ..... 13 



18. Developing fat cells . . . . . . . .13 



19. Columnar ciliated epithelial cells. Showing canalicular apparatus 14 

 20. Successive stages in the movement of an ameba . 15 



21. A leukocyte from human blood in active ameboid motion . . 16 

 22. Three cells from the epididymis of the rabbit . . . .16 



23. Ciliate and flagellate cells .... 17 



24. Successive steps in amitotic division in tendon cell of new-born 



mouse ........ 18 



25. Successive stages in the amitotic division of the ciliated cells lining 



the vasa efferentia of the epididymis of the mouse . . .19 



ix 



