115 



Letdig*), Mojstsovics^), Vejdovskt^), ÜDE*) and Cerfontaine '*). 

 These earlier descriptions are however not discussed in Lenhoss^k's 

 paper. 



A study of sections stained with Kleinenberg's haematoxylin 

 showed plainly the presence of these multicellular sense organs. Each 

 is a bud-shaped group of cells, enclosed in a single layer of slightly 

 modified covering cells. 



The base of each organ contains a few small rounded cells, but 

 the greater part of the organ is made up of elongated sense cells. 

 These sense cells (30 or more in each organ) differ greatly in form 

 from the supporting cells of the epidermis. Each cell tapers toward 

 both ends from an enlarged middle part in which lies the nucleus. 

 The very slender peripheral end passes as a sense hair through a 

 canal in the cuticula covering the sense organ, while its central end 

 either tapers directly into a delicate fibre or else bifurcates several 

 times. 



These sense organs were further studied by means of Golgi's 

 shorter silver method. This showed that the sense cells of the sense 

 organs are distinctly continuous with nerve fibres. These 

 fibres are the continuations of the slender central ends of the cells. 

 In case the central end of the cell is branched, one only of its di- 

 visions gives rise to a nerve fibre. All these fibres pass to the central 

 nervous system without branching, anastomosing, or becoming connec- 

 ted with any other cells. In the central nervous system each fibre 

 divides into cephalic and caudal branches and these branches have 

 free endings. 



The form of the sense cells of these epidermal sense organs, as 

 shown in both haematoxylin and silver-nitrate preparations, is the same 

 as the form of the nerve cells described by Lenhoss^k; the course 

 of the sensory fibres which originate from the sense cells is the same 

 as the course of the fibres which Lenhossek found arising from 

 his nerve cells in the epidermis of Lumbricus. As I have found 



1) Letdig, Ueber Phreoryotea menkeanus. Archiv f. mikr. Anatomie, 

 Bd. ], 1865. 



2) Mojsisovics, Kleine Beiträge zur Kenntnis der Annelliden. Wien. 

 Sitzungsber. math.-naturh, Klasse, Bd. 76, 1877. 



3) Vejbovskt, System und Morphologie der Oligochäten, 1884. 



4) Ude, Ueber die Rückenporen der terricolen Oligochäten. Zeitschr. 

 f. wiss. Zool., Bd. 43, 1886. 



5) Cebfontäine, Recherches sur le Systeme cutane et le Systeme mus- 

 culaire du Lumbricus terrestris. Archiv de biol.. Tome 10, 1890. 



8* 



