x LIST OF ILLUSTRATIONS 



FIGURE PAGE 



26. Multinucleated giant cell, from the yolk-sac of a 10 mm. pig embryo 19 

 27. Spermatocyte of Pj r eris crategi, a butterfly, showing a cilium at- 

 tached to the centrosome 20 



28. Diagrams illustrating successive stages of mitosis . . .21 



29. Cells from epidermis of the salamander 22 



30. Successive stages of mitosis in the root tip of the dogtooth violet 



(Erythronium americanum) 23 



31. Successive stages in the maturation, fertilization and segmentation 



of the star-fish (Asterias forbesii) egg 26 



32. Transverse section of a frog embryo, showing the three germ layers 27 

 33. Group of epithelial cells from the Malpighian layer of the skin . 30 

 34. A villus of the human placenta, showing a peripheral syncytium of 



irregular thickness . . . . . . . .31 



35. Cells from the pancreas of Necturus, containing secretory granules 



and basal ergastoplasmic filaments . . . . .31 



36. Various forms of cells 31 



37. Polyhedral epithelium, from a section of the human liver . . 32 

 38. Goblet and columnar cells from the large intestine of the cat . . 32 

 39. Columnar epithelium from the pyloric region of the human stomach 33 

 40. 'Terminal bars' of cement substance as seen between the epithelial 

 cells of a tubular secreting gland in the pyloric region of the 

 human stomach ......... 34 



41. Semidiagrammatic illustration of endothelium lining a large artery 37 

 42. Mesothelium (surface view) from the mesentery of a rat . . 38 

 43. Cuboidal epithelium from the rete testis of the rabbit ... 39 

 44. Tip of a villus of the synovial membrane from the knee-joint of an 



old man 39 



45. Columnar ciliated epithelium from the epididymis of a rabbit . 40 

 46. A group of cells from a transection of an acinus of the human pan- 

 creas; glandular epithelium 4i 



47. Goblet cells as seen in a transection of a crypt of the large intestine 



in man . . . . . . . . . .42 



48. Diagram showing the arrangement of the columnar and goblet cells 



of figure 47 42 



49. Stratified epithelium from the human esophagus ... 43 



50. Epidermis of the skin of the finger tip, showing extreme keratization 



of the epithelium 45 



51. Pseudostratified columnar ciliated epithelium from a bronchial tube 



of man 46 



52. Diagram showing the manner in which all the epithelial cells of 

 pseudostratified ciliated epithelium reach the basement mem- 

 brane 46 



53. Transitional epithelium from a transection of the ureter of an infant 47 



