CAPILLARIES IN INTEGUMENT OF MEDICINAL LEECH. 308 
On Intra-Epithelial Capillaries in the Integument 
of the Medicinal Leech. By E. Ray Lankester, 
M.A., F.R.S., Professor of Zoology in University Col- 
lege, London. With Plate XXVI. 
I am not acquainted with any minute investigation of the 
structure of the epidermis of the common Leech. Professor 
Leydig has published most valuable accounts of the sense- 
organs of the Leeches, and in a drawing of a transverse sec- 
tion of the medicinal Leech Bau des Thierischen Korpers/ 
Taf. i, fig. 6), has shown the epidermis in position with the 
remarkably enlarged cells which form unicellular glands 
plunging down amongst the muscular bundles far below the 
horizon of the other epidermal elements. The same draw- 
ing also shows a few scattered vessels belonging to the red 
vascular system. These are seen in Professor Leydig’s draw- 
ing to come near the integument, but they do not penetrate 
it. The drawing is on a relatively small scale, so that such 
details as the minute structure of the epidermic cells are not 
presented. 
In sections prepared in my laboratory last year by Mr. 
Blomfield and by Mr. Bourne, and in macerated specimens, 
I have studied the structure of the Leech’s epidermis more 
closely, and have obtained some interesting results. I was 
led to make these observations in carrying out a general plan 
of study of the epidermic tissue in the various groups of the 
animal kingdom. The integument of the Earthworm two 
years ago yielded me some very interesting results entirely 
contradictory to Claparede’s statements on that subject — more 
delicate and varied forms of epithelial cells than are yielded 
by the Earthworm’s epiderm when macerated are not pre- 
sented by any other animal — whilst the whole structure of 
the clitellum and its periodical variation is especially in- 
teresting. Amongst the most important facts established 
in regard to the Earthworm’s epiderm are, firstly, the existence 
beneath the cuticle of a normal cellular matrix, consisting of 
varied forms of goblet cells and excessively delicate elongate 
interstitial or “ packing ” cells, instead of the altogether im- 
probable syncytium described by Claparede ; secondly, the 
penetration in the region of the clitellum of vessels of the 
haemal system in the form of loops between the groups of 
epidermic cells ; thirdly, the similar penetration of processes 
of pigment cells belonging to the connective-tissue system 
among the epidermic cells of the general body-surface (espc- 
