484 MR. F. E. BEDDARD ON THE 
to say very much. The specimen from which my sections were taken, though 
admirable for displaying many points in the histology of the animal, had not 
its hypodermic layer well preserved, the constituent cells were not distinguish- 
able, the whole was visible simply as a granular mass; this may be owing 
perhaps to the fact that the tissues were hardened with alcohol, which PERRIER 
states to be a very poor reagent for displaying the structure of the hypodermic 
cells. But one very important fact in the constitution of the hypodermic layer 
I was able to make out—the presence of capillaries. In a short paper on the 
epidermis of the leech, Professor LaNnKEsTER,* describes and figures capillaries 
in the same situation lying between the epidermic cells, and at the same time 
states the only other annelid in which they had been hitherto found to be the 
earthworm, and there not generally throughout the body wall, but only in the 
clitellum. In Pleurochwta they are very evident, running up through the two 
muscular layers and ending in the hypodermis ; their exact relation to the con- 
stituent cells I was unable to make out, for the reasons already stated, nor 
could I satisfy myself as to their exact mode of ending, though I should pre- 
sume, from analogous cases, that they terminate in loops. In many of my 
sections, especially those stained in aniline blue, the capillaries of the integu- 
ment were most beautifully conspicuous ; the coagulated blood having taken 
up the staining fluid rather more than the surrounding muscles, connective 
tissue, &c. It is very possible that the distribution of capillaries to the outer 
epidermic layer of worms and other animals is much more common than is 
generally supposed, and they may have been in many cases overlooked, owing 
to their insignificant size ; it seems natural that many of these animals without 
a specialised respiratory apparatus, should breathe by means of their skin; and 
this would be greatly facilitated where the epidermis and cuticle are at all 
thick, by a capillary network in the epidermis itself. I intend to direct my atten- 
tion to this point on some future occasion. 
(3) Muscular Coats.—The two muscular layers of the body wall are, as in 
other worms, an outer transverse and an inner longitudinal layer. The 
individual muscles are of various sizes, and appear to resemble in histological 
structure the muscles of other annelids. My observations agree with those of 
CLAPAREDE and Perrier.t The arrangement of the muscles is, however, very 
peculiar, and requires a minute description, as it appears to differ considerably 
from anything that has been yet observed, with the exception of Pontodrilus 
described by PERRIER in the memoir just alluded to. A transverse section 
through the body wall in a direction at right angles to the outer circular layer 
is shown in Plate XX VI. fig. 5. It will be observed, that immediately beneath 
* Quarterly Journal of Microscopical Science, vol. xx. 
+ Archives de Zoologie Experimentale, vol. ix., 1881. 
