86 ARTHUE DENDY. 



Fig. 76. — Through the mid-brain and fore-brain, showing the primary 



parietal vesicle (P. F.) on what is really the left side of the middle line. 

 Yig. 77. — Througli the hind brain and fore-brain, showing the development 



of the ordinary paired eyes. 

 Pig. 78. — Througli the hind brain and stomodseum. 

 Pig. 79. — Through the hind brain and auditory pits. 

 Pig. 80. — Through the trunk, showing the Wolffian ducts and tubules. 

 Pig. 81. — Through the trunk further back, showing the thickening of the 



epiblast on the flanks of the embryo. 

 Pig. 82. — Through the neurenteric canal, placing the hinder part of the 



medullary canal in communication with the posterior enclosed part of 



the alimentary canal. 



Pigs. 83—91. Stage L. 



Pig. 83.— Embryo 47, seen from above as an opaque object in spirit. The 

 yolk-sac and serous envelope have been removed from above the head and on 

 the right, x 10. 



Pig. 84. — Embryo 47, from below, as before. X 10. 



Pig. 85. — Embryo 50, hinder end, seen from above as a transparent object, 

 after staining with borax carmine and clearing in oil of cloves. To show the 

 origin of the allantois. 



Pig. 86. — Embryo 50, hinder end, seen from below, as before. 



Pigs. 87 — 89. — Transverse sections of embryo 50, selected and arranged 

 in order to show the origin of the allantois; Pig. 87 being the most posterior, 

 and Pig. 89 the most anterior. Zeiss A, ocular 1. 



Pig. 90. — Embryo 50. Longitudinal section through the head, nearly in 

 the median plane, but not quite truly vertical ; showing the uotochord and 

 pituitary body. Zeiss A, ocular 1. (The section passes a little on one side of 

 he communication between mid- and hind brains.) 



Pig. 91. — Embryo 50. Similar section on one side of the median plane, 

 showing visceral clefts and head cavities. Zeiss A, ocular 1. 



Pigs. 92, 93. Stage M. 



Pig. 92. — Embryo 51, seen from below as an opaque object in spirit. (The 

 Wolffian ridge and hind limb were not really seen until after the removal of 

 the yolk-sac.) X 10. 



Pig. 93. — Embryo 51, sketched from above while alive to show the vitelline 

 circulation, seen through the serous envelope. X 10. 



Pigs. 94, 95. Stage N. 



Pig. 94. — Embryo 96, seen from below as an opaque object in spirit. The 

 yolk-sac and serous envelope have been removed on the left side of the figure. 

 X 10. 



Pig. 95. — Embryo 96. Part of a median longitudinal vertical section 

 through the head, showing the notochord and pituitary body. Zeiss C, ocular 1, 



