OF THE SOFT PARTS IN EUPLECTELLA ASPERGILLUM. 663) 
Of the specimens of Huplectella from the Challenger collection, preserved in 
so many different ways, those only which were simply preserved fresh in absolute 
alcohol proved suitable for the study of the soft parts. In the specimens which, 
with the adherent sarcode, had been preserved in methylated spirit, as well as 
in the fragments preserved in glycerine after previous treatment with nitrate of 
silver, the soft parts had certainly kept their form and arrangement, but they 
showed little of the detail of structure. In the specimens in picric acid, in the 
specimen preserved in chromic acid, and in that preserved in acetate of potash 
after previous treatment with osmic acid, the soft parts had almost entirely. 
separated from the skeleton, and formed a sediment at the bottom of the vessel. 
In the pieces which had been dyed with carmine, and then preserved in 
absolute aicohol, the soft parts had become so friable as to break in pieces when 
touched. 
The results of my investigations, which I now communicate, are therefore 
almost entirely obtained from the pieces preserved in absolute alcohol, and as 
these pieces were all taken from the side wall of the sponge, I was obliged, in 
order to study the remaining regions of the sponge, and especially the cribriform 
opercular plate, and the end portion which was buried in the mud, to use some 
of the pieces which were not so well preserved, and particularly the large one 
in methylated spirit. 
On the portions which were free from mud and other impurities, the soft 
parts had a pale yellowish-grey colour, and were but scantily developed. They 
consisted of a substance of the consistency of crum of bread, extending between 
the meshes of the framework of siliceous threads and the adherent or free 
siliceous spicules, and the soft matter is traversed by so many passages and 
hollow spaces that it is nowhere compact, but forms rather a delicate meshwork 
of fibres or membranes, This soft substance is most abundant in the tube- 
shaped wall which forms the principal part of the sponge, in the flat thinner 
portion of the tube as well as in the ridges which project from its outer surface, 
and to which the collar-like border of the terminal cribriform plate also 
belongs. 
We see in a well-preserved piece of the tube-wall that the circular apertures 
in the skeleton, which are arranged at pretty equal distances in oblique or 
rather in spiral rows crossing one another, and which mark the angles of 
rhomboidal fields of nearly equal size, correspond also to circular apertures 
about 2 mm. in diameter through the entire wall of the tube, by means of which 
the water surrounding the sponge communicates directly with that contained 
in its inner cavity. 
The margin of these circular wall-openings (as I shall henceforth call them) 
consists of a rather thin ring of membrane, which lies considerably nearer the 
inner than the outer surface of the wall which is nearly 3 mm. thick; so that 
