THE SOMATIC EQUILIBRIUM AND THE NERVE 

 ENDINGS IN THE SKIN. 



By C. L. Herrick and G. E. Coghill. 



PART ONE. 



With Plates V — IX. 



Few problems have proven more attractive or more illusory 

 than the general question as to the nature of the nerve termini 

 in the membranes, for it would seem that our concepts of the 

 histogenesis and so of the real nature of the sense organs de- 

 pend very largely upon the conclusion at which we arrive as 

 to the relation between the various types of sensory epithelium. 

 The senior writer suggested, in a series of papers on the brain 

 of the lower vertebrates, reasons for believing that the first 

 sense to come into the field of consciousness was that of smell, 

 and a little later Edinger emphasized the same idea by his in- 

 vestigations of the olfactory tracts of the reptile brain. It may 

 now be taken as fairly proven that, if the seat of consciousness 

 is in the cerebrum, smell was the first of the special senses to 

 find its way to recognition by it. It would then be natural that 

 we should expect the peripheral organs of olfaction to retain a 

 primitive character and so to afford us a clue to the early state 

 of such organs. Then too the development of the accessory 

 or non-nervous organs of sense has here hardly made any pro- 

 gress even in those most highly differentiated cases in which 

 Jacobson's organ has assumed great proportions. 



From studies of the development of the olfactory organs 

 in reptiles, as reported briefly in earlier numbers of this Journal, 

 the writer has been abundantly convinced of the truth of Beard's 

 statement that the olfactory prota arise from the skin and, by a 



