No. 3. — CONTRIBUTIONS FROM THE ZOOLOGICAL LABORATORY 

 OF THE MUSEUM OF COMPARATIVE ZOOLOGY AT HARVARD 

 COLLEGE, UNDER THE DIRECTION OF E. L. MARK, No. 153. 



The Optic Reflex Apparatus of Vertebrates for SJiort-circuit 

 Transmission of Motor Eeflexes throtigh lleissner's Fibre ; its 

 Morphology, Ontogeny, Phylogeny, and Function. — Pakt I. 

 The Fish-like Vertebrates. 



Introduction 



Morphological 



A. General historical survey . 



1. Reissner's fibre .... 



2. The mesencephalic nichilu 



of optic reflex cells . . 



B. Methods and material . . 



C. The brain ventricles and cen 



tral canal and their content." 

 I. The encephalic cavities . 



1. The cerebro-spinal fluid 



2. Cilia 



8. Ependymal groove . . 

 4. Sense organs .... 



II. Contained material . . 



1. Coagulum 



2. Epithelial cells . . . 



3. Blood corpuscles . . . 



4. Artifacts 



5. The posterior canal cells 



6. Reissner's fibre . . . 



a. Appearance in the fresh 



condition .... 

 h. Appearance in sections 



c. Internal structure 



d. Size 



D. Morphology and ontogeny of 



Reissner's fibre and its cellu- 

 lar c(jnnections 



I. Cyclostomes 



A. Historical 



VOL. xi.v. — NO. 3 



By Porter Edward Sargent, 



TABLE OF CONTENTS. 



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