174 Proceedings of the Royal Physical Society. 



fibril does not pass up the whole length of the interior of the 

 seta ; moreover, from the manner of formation of the seta, it 

 would be difficult to conceive of a continuation of the fibril 

 up the lumen. The granular appearance which Leydig 

 first remarked in the interior of similar setae, and considered 

 to be due to a " nervous substance," is due (when it is pre- 

 sent) to the products of the breaking down of Braun's " hair- 

 papilla." 



There is not, however, such a definite and easily visible 

 point of attachment as that which Hensen describes in the 

 auditory setse, and calls the " lingula " {see his figures 17, 20, 

 30, etc.) ; the manner of attachment is shown in Fig. 12. 

 The nerve is attached or opposed to an oval surface (Hensen 

 describes his " lingula " also as an " extended oval ") a very 

 short distance from the base of the seta, but distinctly in 

 the lumen. The lingula projects slightly into the lumen, 

 and if setse be broken off under the microscope near the base, 

 and a staining agent, such as saffranin, be then applied, it is 

 stained deeply. Of the nature of the mode of attachment, 

 further than that the end of the nerve-fibre lies against this 

 spot, and is evidently intimately connected with it, I can 

 give no account. This nervous connection is evidently 

 homologous with Hensen's " chorda," but differs from it in 

 not being chitinous; and I can only understand what he 

 says about the apparent chitinisation of the '' chorda " before 

 the moult, by supposing that the very delicate nature of the 

 vibrations which the auditory seta has to receive has re- 

 sulted in the production of a transmitting apparatus very 

 different from that of the coarser, and from that point of 

 view less differentiated, tactile seta. 



Glands of the Great Claw. — Scattered thickly among the 

 nerve-endings in the claw, and often lying close against 

 them, are the peculiar bodies to which Braun refers {loc. cit., 

 p. 137) as " Zellennester." Though they do not actually 

 belong to the subject of this paper, I wish to make some 

 remarks on them here, as I may not again have an oppor- 

 tunity of doing so. I can quite confirm Braun's description 

 of them so far as it goes, but would remark that, if he had 

 employed the method of continuous series of sections, he 



