UNIVERSITY OF CALIFORNIA PUBLICATIONS 



ZOOLOGY 



Vol. 1, No. 8, pp. 269-286, Pis. 24-25 December 17, 1904 



THE DISTRIBUTION OF THE SENSE 



ORGANS IN MICROSCOLEX 



ELEOANS 



ISY 



JOHN F. BOVAED 



(Zoological Laboratory, University of Oregon) 



The sense organs of the earthworm were discovered by Ley- 

 dig ('65), who described them as spots, each made up of a group 

 of cells, five or six times larger than the surrounding cells and 

 often times limited by pigment. Mojsisovics (77) was the first 

 to accurately describe these cells. His figures do not show them 

 to be any different from ordinary epithelial cells except for the 

 possession of sense hairs which pass through the cuticle. 

 Schultze, a contemporary of Mojsisovics, has the credit of dis- 

 covering the canals through which the sense hairs protrude. For 

 nearly twenty years the question was debated whether or not 

 these were really sense organs. Cerfontaine ('90) settled this 

 by giving accurate and detailed descriptions and illustrations. 

 He likened the arrangement of cells to the manner in which 

 onion leaves overlap each other. This character may be seen 

 but it is not to be observed regularly throughout the whole 

 worm. Although the connection of these organs to the nervous 

 system was conjectured, the proof was not brought forward 

 until 1895, when Miss Langdon published her paper on the 

 sense organs of Lumbricus in the Journal of Morphology for 

 May of that year. She demonstrated conclusively the direct 

 connections of the cells of the sense organs with the nervous 

 system and described the distribution of these organs over the 

 body. 



