No. I.] SENSE-ORGAIVS OF LUMBRICUS AGRICOLA. 205 



In cross and longitudinal sections, there appear bundles of 

 stained fibres passing to the epidermis through the circular 

 muscle-layer (PI. XIII, Fig. 3). These fibres are often varicose 

 and sinuous, and appear imbedded in or surrounded by an un- 

 stained substance. In sections in which the fibres show at 

 the very base of the epidermis, it is easily seen that they pass 

 throus:h the basement-membrane and become continuous with 

 the fibres of the subepidermal network. Hence the intraepi- 

 dermal nerve-fibres are branches of fibres which approach the 

 epidermis in the same position as the epidermal nerves described 

 in the haematoxylin preparations. As will be seen presently, 

 these fibres are efferent nerve-fibres. These intraepidermal 

 nerve-fibres appeared in every preparation made, and have been 

 found in all regions of the earthworm except in the clitellum, 

 which has not been studied for this purpose; but they appear 

 to be more numerous in the caudal metameres. The fibres 

 have been found between the supporting cells, but appear to 

 be more numerous in those regions in which the gland-cells 

 are more abundant. As these fibres have not been obtained 

 by any other stain, it is not known whether fibers have re- 

 mained unstained in parts of the epidermis where they have 

 not been seen. However, the great readiness with which these 

 fibres took the stain would seem to oppose this idea. No intra- 

 epidermal fibres have been found in the sense-organs, and they 

 are not numerous in their immediate vicinity. This latter fact 

 is probably connected with the absence of gland-cells in the 

 immediate vicinity of a sense-organ. 



Between the cells of the epithelium lining the buccal cavity 

 are nerve-fibres which are similar to the intraepidermal fibres 

 (PI. XIII, Fig. 10). The epithelium cells and the cuticula cover- 

 ing them is never stained, consequently the endings of these 

 fibres can be seen more readily than in the epidermis (PI. XIII, 

 Fig. 7). Some fork once; many end in what appears to be a 

 flat plate, but it is impossible to state that this is anything dif- 

 ferent from the "artefacta" often seen in the course of a fibre. 

 These fibres in the buccal epithelium may be traced to the 

 cephalic ganglia or aesophageal ring. 



The greater abundance of the intraepidermal fibres in regions 



