190 



DEVELOPMEXT OF THE FROG'S EGG 



Nervous system, central, 159-161. 

 Neural crest, 159, 160. 

 Neural ridge or crest, 16.3, 164. 

 ^Neurenteric canal, 1.38-140. 

 Newport, absorjition 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. 



Pfliiger, 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. 

 j, 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 gi-oove, 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 temiwraria, 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. 

 Retiua, 161. , 

 Robinson, formation of archenteron, 



70. 

 Rotation of egg, 83-85. 

 Roux, artificial fertilization, 32. 



