AUTHOR S ABSTRACT OP THIS PAPER ISSUED 

 BY THE BIBLIOGRAPHIC SERVICE, AUGUST 7 



NEUROMERES AND METAMERES 



H. V. NEAL 



Department of Biology, Tufts College, Mass., and the Harpswell Laboratory, South 



Harpswell, Maine 



SEVENTEEN TEXT-FIGURES 



Two interpretations of the so-called neuromeres of vertebrate 

 embryos have been suggested: 



1, The non-phylogenetic interpretation that neuromeres are 

 either a) artifacts .due to the action of fixing agents or, b) 

 transient embryonic structures resulting either from longitu- 

 dinal compression of the neural tube or to the local strain of 

 related nerves. 



2. The phylogenetic interpretation that neuromeres are the 

 visible remnants of a primitive segmentation of the nervous 

 system and consequently reliable clues to the original number 

 of metameres in the vertebrate head. 



Which of these interpretations are we to accept? Are neuro- 

 meres reliable criteria of the metamerism of the vertebrate head? 

 The present paper attempts to give an answer to these questions 

 on the basis of the evidence presented by the central nidular 

 relations of the motor cranial nerves, as disclosed in Bielschow- 

 sky-Paton and Cajal-Ranson preparations of Squalus embryos, 

 and upon the data supplied by comparative embryology. The 

 literature dealing with the neuromeric problem has been so 

 thoroughly reviewed by Kupffer ('05, '06), Griggs ('10), Graper 

 ('13), and Smith ('14) that a critique and review seems super- 

 fluous at this time, and we may therefore pass at once to a dis- 

 cussion of the problem. 



The supposition that neuromeres are artifacts produced by the 

 action of killing and fixing fluids may be dismissed at once as 

 erroneous on the ground that neuromeres are visible in the liv- 

 ing embryo. That they are the purely mechanical result of the 



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THE JOURNAL OF MORPHOLOGY, VOL. 31, NO. 2 



