CONTENTS. 



I. Introductory 



II. Review of literature 



The comparative anatomy of the menin- 



ges 



Literature on the development of the 

 mammalian meningeal spaces 



III. Methods of investigation 



IV. Injections and replacements in the cerebro- 



spinal system 



Results of replacements in the ventricular 



system of true solutions 



The results of injections of true solutions 

 Results of injections of nitrate of silver. . 



The injection of india ink 



V. Undescribed structures in roof of the fourth 



ventricle 



An undescribed area in the superior por- 

 tion of the roof of the fourth ventricle 

 The area membranacea superior in the 



pig embryo 



The area membranacea superior in the 



human embryo 



The area membranacea superior in 



other animals 



General consideration of the area 



membranacea superior 



An undescribed area in the inferior por- 

 tion of the roof of the fourth ven- 

 tricle 



The area membranacea inferior in 



the pig embryo 



The area membranacea inferior in the 



human embryo 



General consideration of the area 



membranacea inferior 



VI. Passage of fluid through roof of the fourth 



ventricle 



The accumulation of injection-masses in 



the superior membranous area 



The sites of fluid passage through the 

 roof of the fourth ventricle 



PAGE. 



Passage of fluid through roof of the fourth 



ventricle Continued. 

 Factors concerned in the experimental 



fluid passage 57 



The passage of silver nitrate and india 

 ink through the membranous areas 

 in the roof of the fourth ventricle. . . 60 

 Relation of the ependymal differentiation 



to the passage of fluid 61 



General histological differentiation of the 



cerebro-spinal spaces 63 



The periaxial mesenchyme 63 



The formation of the arachnoidea 64 



The circulation of fluid through the 



subarachnoid spaces 70 



A consideration of the embryonic pia mater. 71 

 The general histology of the pia mater. . 72 

 The relation of the pia mater to the fluid 



channels 73 



The adhesion of the pia mater to the cere- 

 bral tissue 75 



The development of the cranial dura mater . 75 

 The general process of the formation of 



cranial dura 76 



The subdural space and the mesothelial 



lining of the dura 85 



The competency of the early dura as a 



cellular membrane 87 



The return of cerebro-spinal fluid to the 



venous system 88 



The chorioid plexuses and the elaboration 



of cerebro-spinal fluid 91 



The development of the chorioid plexuses 91 

 The glycogen content of the chorioid 



plexuses 93 



Perivascular spaces in the embryo 95 



The perineural spaces in the pig embryo. . . 97 



General summary 101 



Conclusions 107 



Bibliography 109 



Explanation of plates Ill 



