2 26 LANGDON. [Vol. XI. 



present on a few anterior metameres only, and the sense of 

 touch highly developed over the whole body. Leydig {'65) 

 seems to have regarded the sense-organs as " Geschmacks- 

 knospen." Vejdovsky {'84) objected to this, and thought them 

 " Tastorgane," an opinion which is shared by Ude ("86). Vogt 

 and Jung {'88) stated that Lumbricus perceived light and sojind. 

 It is likely that they mistook the great sensitiveness of this 

 worm to mechanical disturbance for an ability to perceive 

 sound. Retzius, in writing of the probable function of the 

 " Sinnesnervenzellen," says, " Der Regenwurm besitz keine 

 anderen, hoher entwickelten Sinnesorgane ; er ist aber be- 

 kanntlich fiir Sinnesreize verschiedener Art empfindlich. Es 

 ware deshalb von ausserordentlich hohern biologischen In- 

 teresse zu erfahren, ob dieselben Sinnesnervenzellen diese ver- 

 schiedenen Eindriicke vermitteln, oder ob einzelne derselben 

 eine besondere physiologische Function haben." Since these 

 sense-organs form the only known sensory apparatus of Lum- 

 bricus, and since their structure is not visibly different in dif- 

 ferent parts of the body, it is likely that they are sense-organs 

 of a general nature capable of reacting to mechanical, chemical, 

 thermal, or luminous stimuli. Those situated in the buccal 

 cavity doubtless serve principally as organs of taste. The 

 presence of a thick layer of pigment in the dorsal epidermis of 

 the head metamere suggests an explanation of the fact that 

 light is perceived only on the anterior metameres. Lenhossek 

 homologized his nerve-cells with ganglion-cells of the dorsal 

 roots of the spinal nerves. 



Intraepidermal nei-ve- fibres. — Lenhossek {'92) brought up 

 the question of intraepidermal nerve-endings but to decide 

 against the possibility of their presence. After an examina- 

 tion of a large number of preparations, he stated, "kann ich nun 

 das Vorkommen einer freien Nervenendigung in der Haut des 

 Reerenwurms mit grosser Wahrscheinlichkeit ausschliessen." 

 As these intraepidermal nerve-fibres have appeared in every 

 one of my sections, I can account for the fact that they were 

 not seen by Lenhoss6k only on the assumption that the sil- 

 ver stain produced somewhat different results in his hands 

 and in mine. That there was a difference in our results is 



