SEA-FISH@ERIES LABORATORY. 398 
the centre (fig. 50, A/."); their protoplasm has practically 
disappeared, there are just a few strands left crossing the 
cells which contain the green pigment granules clustered 
together in little groups. The connective tissue membrane 
bounding the alveolus has here become very’ thin, and the 
circular muscles have practically disappeared. MacMunn 
(21) has termed the green pigment enterochlorophyll, and 
finds that the spectrum given by the spectrophotometer 
is almost exactly that of plant chlorophyll modified by the 
addition of a little acetic acid acting for several hours. 
Tle considers, therefore, the pigment to be modified 
chlorophyH. Miss Newbigin considers the resemblance 
of this pigment to chlorophyll to be only superficial, and 
places it in the same category as Chaetopterin and 
Bonellin. 
It is, however, almost certain that the colour of 
the digestive gland at any time is dependent on the colour 
of the food, and several observers, including List and 
Dastre and Floresco (6 and 19), have shown that if 
Lamellibranchs are fed with colouring matter this appears 
in the form of small granules in the cells of the digestive 
oland, and even after two hours can be traced there. List 
shows, further, that it 1s a direct absorption, and not a 
function of the wandering cells. 
In order to determine the action of the secretion of 
the digestive gland, the following bio-chemical experi- 
ments were undertaken. They confirm those of Roaf (22) 
on the glands in other molluscs. 
The glands were taken from several Pecten, the 
whole mass weighed and then minced up in a definite 
volume of distilled water to which a little HCN (or toluol 
when testing for sugar) was added as a preservative. This 
was allowed to stand for twenty-four hours and then 
strained through muslin and a series of solutions made 
