238 PROFESSOR F. M. BALFOUR. 



inner, appear to be continued to the end of the spines. Within 

 the base of the spine there is visible a finely striated substance 

 which may often be traced into the cavity enclosed by the cells, 

 and appears to be continuous with the cells. Attached to the 

 inner ends of most of the capsules of these organs a delicate 

 fibrillated cord may be observed, and although I have not in 

 any instance succeeded in tracing this cord into one of the nerve- 

 stems, yet in the antennae, where the nerve-stems are of an 

 enormous size, I have satisfied myself that the minute nerves 

 leaving the main nerve-stems and passing out towards the skin 

 are histologically not to be distinguished from these fibrillated 

 cords. I have therefore but little hesitation in regarding these 

 cords as nerves. 



In certain regions of the body the oval aggregations of cells 

 are extremely numerous ; more especially is this the case in the 

 antennae, lips, and oral papillae. On the ventral surface of the 

 peripheral rings of the thicker sections of the feet they are 

 also very thick set (fig. 20 p). They here form a kind of pad, 

 and have a more elongated form than in other regions. In the 

 antennae they are thickly set side by side on the rings of skin 

 which give such an Arthropod appearance to these organs in 

 Peripatus. 



The arrangement of the cells in the bodies just described led 

 me at first to look upon them as glands, but a further inves- 

 tigation induced me to regard them as a form of tactile organ. 

 The arguments for this view are both of a positive and a nega- 

 tive kind. 



The positive arguments are the following : 



(1) The organs are supplied with large nerves, which is dis- 

 tinctly in favour of their being sense organs rather than 

 glands. 



(2) The peculiar striae at the base of the spines appear to me 

 like the imperfectly preserved remains of sense hairs. 



(3) The distribution of these organs favours- the vicAV that 

 they are tactile organs. They are most numerous on the an- 

 tennae, where such organs would naturally be present, especially 

 in a case like that of Peripatus, where the nerve passing to 



