A. W. WATERS—REPORT ON THE BRYOZOA. 155 
LL. occlusa, and generally in the oral glands. Attention may be called to the 
fact that the glands, as a rule, occur in all the zocecia, and are not dependent 
upon the sexual condition of the zocecium, so that they do not seem to be 
connected with sexual processes. However, in Lepralia cucullata, Busk, 
which has a concealed ovicell (PI. 15. fig. 4), the glands only begin to grow 
when the ovicell is forming. In L. occlusa the gland is formed in the 
youngest zocecia, when the polypide is quite immature, and it looks like 
a growth from the tentacular sheath. 
There is no absolute proof as to the function of the glands, and some 
experiments I made many years ago on feeding with colours were not satis- 
factory, for the difficulties when dealing with opaque calcareous organisms 
are very great. Calvet™, however, states that he has not found that the 
glands absorb colour. There has always seemed much to suggest their 
being excretory organs, and in animals without a circulatory system we 
must not expect any such organ to exactly resemble those where there is 
an active circulation, nor with such glands surrounded by a membrane must 
we take it for granted that colour would be absorbed in the same way. The 
position f and varying shape also suggest comparison with salivary glands 
of insects, worms, &ec., but we are confronted by the fact that there are similar 
glands in the avicularia ; now these have no digestive organs, whereas the 
salivary glands are supposed to have a digestive function. 
T have induced my friend Mr. Henry Waddington, F'.L.8., to grow some 
Bryozoa in his aquarium in order to study this organ in specimens in perfect 
condition, and perhaps with his success in keeping marine animals, and his 
skill in microscopical manipulation, he or we may be able to throw light on 
the function of the organ. 
However, to return to what we definitely know. There is a secreting- 
gland, having very different forms in various species, which pours out the 
secretion close to the diaphragm, that is at the external opening. Should 
proof be found that these glands only remove waste products, then I suppose 
they must be called excretory. 
Very minute excretory organs are known in Lowosoma and Pedicellina, 
and have been described by Nitsche, Hatschek, Joliet, Harmer, Fottinger, 
Ehlers, Prouho, Schulze, and Gustay Stiasny f, who have cleared up points 
which were still uncertain; also Cori and others have considered that 
excretory organs occur in the Phylactolemata ; there is, however, no simi- 
larity between these small organs and those of the Cheilostomata. 
* “Bryozoaires Ectoproctes Marins,’ p. 286 (1900). 
t The similarity is perhaps not so great as appears at first sight, for the glands are not 
attached directly to the movable polypide, but to the zocecium which contains it, and it 
should be remembered that what is called the diaphragm is really a sphincter. 
t “Beitrag zur Kenntniss des Exkretionsapparates der Entoprocta,” Arbeit. zool. Inst. 
Wien, vol. xv. p. 183, pl. 1 (1905). 
LINN. JOURN.—ZOOLOGY, VOL, XXXI. 12 
