STliUOTURE AND DEVELOPMENT OP REISSNER’s PEPRE. 1 
The Structure and Development of Reissner’s 
Fibre and the Sub-commissural Organ. 
Part I. 
By 
Ceorso K. IVicliolls, IS.Sc., 
Professor of Biology at the Agra College, Univ^ersity of Allahabad. 
(From the Zoological Department, King's College. University 
of London.) 
With Plates 1 to 5 and 8 Te.xt-fignres. 
Contents. 
I. Preface ...... 
II. Introduction . . . . . 
(a) Methods and Material . . . . 
(h) Historical Review . . . . 
(c) General Introductory Account of the Actual Rela- 
tions of Reissner's Fibre and the Suh-oommissural 
Organ ...... 
(d) Critical Discussion of tlie Views of Sargent and 
Houser . . 
III. Reissner’s Fibre and the Sub-commis.sural Oroan 
IN THE PeTROMYZONTID.® . . . . 
Petromyzon fluviatilis. 
The Sub-commissural Organ 
Reissner's Fibre .... 
The “ Dachkern ” . 
Geotria australis . . . . 
Development ..... 
Ichthyomyzon (Entosphenus) tridentatus . 
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