No. I.] SEA^SE-ORGANS OF LUMBRICUS AGRICOLA. 203 



A St7idy of the Epidermis by Means of Golgi's Silver Nitrate 



Method. 



Effect of the stain on epidermis in general. — In sections 

 prepared by this process, the cuticula was usually stained black 

 and a black precipitate deposited beneath it. This rendered 

 difficult a study of that portion of the epidermis just beneath 

 the cuticula. The supporting cells remained clear or were 

 stained a uniform black ; in the latter case their basal processes 

 were readily seen. The gland-cells were never stained either 

 wholly or in part, but they could be easily distinguished because 

 of their shape and contents. The basal cells were never stained. 

 Sometimes the basement-membrane was obscured by a thick 

 deposit of silver, but it generally showed with perfect clearness 

 as an unstained, apparently structureless layer between the 

 epidermis and the circular muscle-layer.^ 



Intraepidermal nei've-fibres. — The most striking feature in 

 these sections is the presence of more or less deeply stained 

 fibres betiveen the epidermal cells, and in no instance connected 

 with the bases of these cells (PI. XIII, Figs. 3, 5, and 6). That 

 these fibres are nerve-fibres there can be no doubt. That 

 these are really fibres and not the edges of lamellae formed by 

 the deposit of silver in intercellular spaces may be shown by an 

 examination of sections which pass obliquely through the epi- 

 dermis. Between the cell walls are seen sections of these 

 fibres appearing as black dots ; as the course of the fibres is 

 oblique to the surface of the section, they may be traced down 

 by focusing, and seen to be really fibres. That these are nerve- 

 fibres is shown by two facts ; first, by the fact that they pre- 

 sent precisely the same appearance as undoubted nerve-fibres 

 which are found among the muscles and in the central nervous 

 system — the appearance of a clear, glistening thread sur- 



1 In all my preparations the blood-vessels among the circular muscles show 

 distinctly either stained or unstained. These blood-vessels press closely against 

 the basement-membrane, forming here great loops and coils. Lenhossek ('92) 

 stated that the blood-vessels in his preparations enter the epidermis itself. Al- 

 though I have searched my preparations carefully, I have found no instance of 

 this outside of the clitellum. Lenhossek has a later paper (Die intraepidermalen 

 P.lutgefrisse in der Haut des Regenwurmes, in Verhandl. Naturf. Gesell. Basel, 

 Bd. 10, Heft I, p. 84) which I have not seen. 



