THE HARVEIAN ORATION. 



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precisely the same morphological importance— has often been figured 

 as existing in the hearts of most or all Reptilia below Crocodilina ; 

 and it serves in them to close up and expel the blood from the 

 pulmonary compartment of their imperfectly divided ventricle. 



Fig. 2. — Heart of Sheep. The right ventricle is laid open. The letter M 

 indicates the moderator band. A probe has been passed between the chordae 

 teiidineae, passing from a musculus papillaris arising from the movable wall 

 of the ventricle to the two main segments of the tricuspid valves and the 

 outer wall of the ventricle. 



Such being the function of this moderator band, what is its mor- 

 phological bearing, and what traces can we find of it in ourselves, 

 tempting us to speculate as to the nature of the secret bond which 

 brings us into relations of affinity not only with the mammalian class, 



3 B 3 



