34 Moll. 
MOI^LUSCA. 
organ in all groups, that the author thinks it must have a common func- 
tion, which is probably not glycogenous ; Fbenzkl (2). 
The oesophageal glands of Octopus resemble bunches of grapes in 
section, and consist of abundant interstitial tissue, an amorphous matrix, 
fusiform cells, capillaries, nerve-fibres and sheaths round the ducts ; the 
excretory canals have au opaque striated lining, and the gland is not 
acinous but a ramified tube. The terminations of the tubes contain very 
granular polyhedral cells, while higher up are elongated cells ; perhaps 
different states of the ferment-producing cells. The excretory canals are 
lined by a single layer of opaque balls, each of which is striated and sur- 
rounded by a clear zone in which is a nucleus. The gland probably 
secretes both mucin and ferment ; Pilliet. 
Apathy confirms the existence of mucous cells in TJnis (which Kollmann 
regarded as interstitial spaces) ; they are disposed iu groups, and are 
connected with an efferent duct ; each cell has not its own duct, as was 
erroneously stated by Carriere. 
In the Pulmonata the organ of Bojanus presents great structural 
analogy with the lung ; it does not receive arterial blood from the aorta, 
but a small amount of venous from the general cavity and a much larger 
quantity of arterial from the lung ; this latter is concentrated in a receiver, 
extending the whole length of the organ above the excretory canal, hence 
it is distributed in the lacunse of the walls of the organ, where it mixes 
with the venous blood of the general cavity. The blood which has 
circulated thus always returns to the pulmonary vein by one or more 
canals. It is possible that the organ of Bojanus, in addition to its 
primary functions, plays an important partin respiration and circulation; 
Amaudkut (2). 
MacMunn (3) describes a method of obtaining uric acid crystals from 
the nephridium of Pulmonata ; in Helix aspersa the crystals were of 
various shapes, the size depending on the mode of preparation ; similar 
crystals which exhibited the murexide reaction were got from Limax 
Jtavus. In the juice of the nephridium of Helix there are spherical 
crystals, regarded by some observers as bile-pigment : they probably con- 
sist, however, of urates of calcium and sodium. Their central portion 
consists of radially-disposed needles. 
In the same author’s (1) extensive paper on Enterochlorophyll there 
are some incidental references to the pigments of Mollusca. On haemato- 
porphyrin in the integument of Lirnax, cf. id. (4). 
• The byssus gland and the attachment of Lamellibranchs to foreign 
bodies, are described by Cattie in a considerable number of species ; the 
walls of the byssus-cavity secrete constantly ; the lamellae iu the anterior 
portion fuse to form the trunk of the byssus (“ round tendon ” of Reau- 
mur). When the orifice of the cavity is less distinct, the lamellae of the 
byssogenous material alternate with lacunae. The epithelium of the 
byssus cavity is generally ciliated ; glandular cells are disposed around 
it, and an increased surface is sometimes obtained by the plication of the 
walls. The author does not believe in the inception of water through pores 
in the foot. 
The byssus of Pelecypoda is peculiar to the group, and secreted by 
