114 



Zum Schlüsse halte ich es für meine angenehme Pflicht, meinem 

 hochverehrten Lehrer, Herrn Geh. Rat Professor Gegenbaur, für die 

 Gewährung aller Hilfsmittel zur Beendigung dieser Arbeit nochmals 

 meinen herzlichsten Dank auszusprechen. 



Nachdruck verboten. 



The Sense Organs of Lnmbricus agricola Hoffm. 



Preliminary Notice *) 



by Fanny E. Langdon. 



From the Morphological Laboratory of the University of Michigan, 



under the direction of Professor Jacob Reighaed. 



In December 1891 sections of Lumbricus agricola Hoffm. were 

 prepared in the Laboratory of Animal Morphology of the University 

 of Michigan, in which the epidermis presented in many places an 

 arrangement of cells apparently identical with that which is found in 

 the vertebrate taste-bud. At the suggestion of Professor Reighard 

 the writer and Miss M. F. Randolph undertook an examination of the 

 literature and a study of the structure, nerve supply and distribution 

 of these apparent sense organs. Miss Randolph did not return 

 the next year so that the work has since been carried on by the 

 writer. 



While the work was in progress there appeared a paper by Len- 

 HOSSEK ^) in which he describes in the epidermis of Lumbricus a sen- 

 sory apparatus composed of isolated nerve cells, which give rise to 

 sensory fibres. The latter end freely in the central nervous system. 

 Lenhossek believes that these isolated nerve cells account for the well- 

 known sensitiveness of the epidermis of Lumbricus, that they are 

 never grouped into sense organs, and that the epidermis is without free 

 nerve endings. Retzius ^) confirms Lenhossek's work. 



Our examination of the literature brought out the fact that multi- 

 cellular epidermal sense organs had been described in Lumbricus by 



1) An abstract was read before the American Society of Morpho- 

 logists at the New Haven meeting, December 1893. 



2) Lenhossek, Ursprung, Verlauf und Endigung der sensiblen Nerven- 

 fasern bei Lumbricus. Archiv f. mikr. Anatomie, Bd. 39, 1892. 



3) Eetzius, Das sensible Nervensystem der Polychäten. Biol. Unter- 

 suchungen, N. F. Bd. 4, 1892. 



