HISTOLOGY OP THE LAND-PLAN ARIANS OP CEYLON. 
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yellow, black, and brown, and exists as minute rounded particles embedded more or less 
thickly in multiramified, transparent, and homogeneous protoplasmic masses : these proto- 
plasmic elements (Plate XI. fig. 1) have usually a larger or main mass, which lies 
almost immediately beneath the external muscular system, in the same position as that 
occupied by the parent cells of the rod-like bodies ; and from this main mass as a 
centre they send out fine branched thread-like processes, which ramify amongst the 
loose radiating muscular elements and the gland-tissue, and sometimes penetrate as far 
as between the fibres of the internal muscular system, and occasionally pass outwards 
in an opposite direction a short distance between the epidermic elements. These 
masses are sometimes densely crowded with pigment-granules, which are very dark 
and well defined ; sometimes they contain hardly any at all ; and occasionally 
the pigment-granules are absent from a circumscribed spot on the principal mass, 
which gives the spot the appearance of a nucleus. Kefebsteet (loc. cit. p. 15) 
speaks of the pigment of Planarians as being soluble in alcohol ; such is certainly 
not the case with that of Bipalimn or Rhynchodemus , nor with the eye-pigment, at least, 
of Leptoplana. A Leptoplana which had been preserved in spirit for several years had 
the eye-pigment in perfect condition. The pigment-masses occur more or less irregu- 
larly all over the body in Bipalium Diana and B. Ceres , except on the ambulacral line, 
which is quite free from them. Where there are well-defined stripes on an animal’s 
body the pigment is arranged accordingly ; and thus in the transverse section of Rhyn- 
chodemus (Plate X. fig. 7) the dark spots are seen to be gathered up into three lines, 
one median and two lateral, corresponding to the three dark stripes on the animal’s 
back. 
Glandular Tissue. — The same zone which contains the pigment-cells and parent cells 
of the rod-like bodies is also thickly beset with elongated, irregular, and more or less 
branched masses, which stain themselves an intense colour with carmine, and are filled 
with coarsely granular contents. It is these bodies which were said to be observed to 
be continuous with similar irregular projecting masses found amongst the epidermis 
(Plate X. fig. 10), and which were considered to be slime hardened by the action of 
alcohol in the act of its ejection by the subcutaneous glandular bodies just described. 
These glandular bodies ramify often in an arborescent manner, but do not run into such 
fine threads as the pigment-masses ; there is no nucleus to be detected in them. They 
are not confined to the zone here under consideration ; they are also present in greater 
or less quantity all over the body, even in the septa between the intestinal diverticula, 
and especially abundant in a region just exterior on each side of the body to the testes. 
In Rhynchodemus they are developed internally to a much greater extent than in 
Bipalium,- as will be seen by a comparison of figs. 5 & 7, Plate X. ; they are also very 
conspicuous in preparations, from their being so deeply stained with carmine. 
The internal masses of this gland-substance present slight differences from those 
which are external and subcutaneous. Thus their contents are on the whole less 
coarsely granulated, and their processes finer. In the main water-vascular canal, which 
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