190 



DEVELOPMENT OF THE FROG'S EGG 



Nervous system, central, 159-161. 

 Neural crest, 159, 160. 

 Neural ridge or crest, 163, 164. 

 Neurenteric canal, 138-140. 

 Newport, absorption of water by egg- 

 membranes, 19. 



entrance of egg into oviduct, 16. 



median plane of embryo, 42. 

 Newt, fertilization of, 24. 

 Notochord, 70, 73, 74. 



of spina bifida, 76-78. 



half, 108. 



origin of, 146. 

 Nuclei, distribution in compressed egg, 



104, 105. 

 Nucleus, control of cell by, 128. 



qualitative division of, 129. 

 Nussbaum, entrance of egg into ovi- 

 duct, 16. 



Oil-drops, 43-47. 

 Oogenesis, 12. 



and spermatogenesis, comparison 



of, 13, 14. 

 Optic lobes, 160. 

 Optic stalk, 162. 

 Optic vesicles, 160, 161. 

 Orientation of egg, 81. 



Pelobates, cross-fertilization, 26. 



Pericardium, 151. 



Pfltiger, cross-fertilization, 26-28. 



median plane of embryo, 42. 



blastopore, 51-53, 56. 



account of experiments, 81-89. 



methods, 82. 



conclusions from experiments, 87- 

 89. 



compression of egg, 95. 



conclusions from compressed egg, 

 101, 102. 



cleavage-plane and embryo-axis, 



108. 



Pharynx, 62, 145. 

 Pigment, distribution of, 15. 



rotation of, 83. 

 Pineal body, 160, 161. 

 Pituitary body, 161. 

 Plane of embryo, median, 42. 

 Pneumogastric nerves, 164. 

 Polar body, first, extrusion of, 16-18. 



second, 21. 



in inverted egg, 91. 



Polarization of egg, 88. 

 Poles of egg, 81. 

 Polyspermy, 30. 

 Post-anal-gut, 141. 



Postgeneration, 110, 111, 116, 128, 

 129. 



of archenteron, 111. 



of medullary folds, 111. 



of mesoderm, 111. 



of ectoderm, 111. 



of whole embryo, 122. 

 Provost, account of cleavage, 48. 

 Primitive groove, 57, 72. 

 Primitive segments, origin of, 147. 

 Proctodaeum, 141, 158. 

 Pronephric capsule, 156. 

 Pronephros, 155-158. 

 Pro-nucleus, union, 23. 



apposition of, 35. 



Rana arvalis, cross-fertilization, 27, 



28. 

 Rana esculenta, spermatozoon of, 11. 



cross-fertilization, 26-28. 



effect of light, 170. 



Rana fusca, extrusion of polar body, 

 21. 



cross-fertilization, 26-28. 



inversion after first cleavage, 116- 

 118. 



effect of temperature, 168, 169. 

 Rana temporaria, egg-laying, 17. 



time of egg-laying, 168. 



effect of light, 169, 170. 

 vom Rath, spermatogenesis of Gryllo- 

 talpa, 2-4. 



spermatogenesis of Salamandra, 5, 

 7. 



tetrad formation in Salamandra, 8. 



spermatogenesis of frog, 10. 



direct division of germ-cells, 12. 

 Rauber, interchange of nuclei, 30. 



segmentation, 39. 



effect of gravity, 90. 

 Reichert, account of cleavage, 49. 

 Remak, segmentation, 38. 



account of cleavage, 49. 

 Reorganization, 109, 110. 

 Retma, 161. 

 Robinson, formation of archenteron, 



70. 



Rotation of egg, 83-85. 

 Roux, artificial fertilization, 32. 



