120 
ME. H. N. MOSELEY ON THE ANATOMY AND 
elusion that the curiously and often spirally contorted appearance of these parent cells 
was merely due to the action of spirit on a highly elastic investing membrane, and the 
bodies shown in fig. 8 were merely debris of such a membrane. In Mhynchodemus these 
cells may often be observed uncontracted and of an oval form, and containing two or 
three rod-like bodies (Plate XI. fig. 2), in fact in every way resembling the rod-cells 
described from ordinary aquatic Planarians. On treatment with potash, the cells of 
Bipalium swell up (Plate XI. fig. 4), are seen to contain rod-like bodies, and the fine 
filament at the upper extremity appears like a duct leading to the surface of the base- 
ment membrane. In sections of the integument taken parallel to the surface, the parent 
cells of the rod-like bodies are seen to occupy positions opposite the interval between 
the stout external longitudinal muscular fibres (Plate XI. fig. 5); and when cut 
through transversely (Plate X. fig. 11), they prove to be divided into two or three com- 
partments, and to be provided with a very stout horny-looking cell-wall. In vertical 
sections they are usually seen to contain more than one rod-like body, often three, in 
apparently different stages of development. The cells have usually a nucleus-like 
body at their inferior extremity. The rod-like bodies and their parent glands are 
distributed all over the body, except on the ambulacral line and the special sense-line 
on the anterior margin of the head ; they are far less numerous on the under surface 
of the body than on the upper. There can be very little doubt that the organs here 
described are the homologues of the well-known “ Stabchen-Organe ” of aquatic Plana- 
rians ; and it is almost certain that the organs described by Mecznikow as existing in 
Geodesmus bilineatus come within the same category. He makes a great point of saying 
that Geodesmus has no “ Stabchen-Korperchen,” but has “ Nessel-Organe.” The only 
difference is that his rod-like bodies are pointed instead of blunt. It may fairly be con- 
cluded that these peculiar skin elements in all Planarians, and probably in all Turbellaria, 
are homologous, though they differ more or less in details of structure. Whether these 
bodies are also homologous with the nettle-cells of Coelenterata is another question, and 
one which will not here be discussed ; it has been fairly gone into by Gegenbaur (loc. 
cit. p. 171) and by Max Schultze (loc. cit. 1, p. 15). 
I much regret that I did not carefully examine the skin-organs of Bipalium in the 
fresh state whilst I was in Ceylon ; but I am not certain that I should have derived 
much benefit, for I am more and more convinced that the study of tissue in the fresh 
condition should succeed and not precede that of sections of the hardened structures in 
all histological investigations of soft parts. It is only when a thorough knowledge of 
the relations and relative sizes &c. of the various elements has been gained in prepa- 
rations in which they may be observed in situ , that we are able to derive much infor- 
mation from the investigation of tissues in the recent state. 
Pigment. — The pigment of the body is entirely confined to this, the subcuticular, 
region, if we except a certain small amount of liver-like pigment to be found in some 
diverticula of the digestive organs. The pigment, as in the medicinal leech (Leuckart, 
loc. cit. p. 638) and in other Planarians (Max Schultze, loc. cit. 1), is of three colours, 
