the cuvierian organs of holothuria nigra. 301 
Note on the Mechanism of Discharge of the 
Cuvierian Organs of Holothuria nigra. 
By 
George Ualpli Mines, M.A., 
Fellow of Sidney Sussex College, Cambridge. 
(From the Laboratory of the Marine Biological Association, Plymouth.) 
With Plate 26. 
It is well known that when Holothuria nigra (the large 
sea-cucumber common at Plymouth) is irritated, it responds by 
emitting; a number of white conical bodies. These, the Cuvierian 
organs, rapidly elongate, shooting through the water while 
remaining attached at their bases to the animal, to form long, 
intensely sticky tubes. The phenomenon has been described 
by Minchin (1), Barthels (2), Herouard (3) and others, but 
there appears to be much divergence of opinion as to the 
mechanism by which the elongation of the tubes is brought 
about. Herouard ascribes it to the forcible iujection of the 
tubes with water, while Minchin denies that water-pressure 
plays auy part in the discharge, and attributes the whole affair 
to the intrinsic activity of the organs themselves. The latter 
view is adopted by Sedgwick (4). 
The observations on which MinchiiFs explanation is based 
are these : If the tubes, when first emitted by the animal, are 
cut off, they continue to elongate. Undischarged Cuvierian 
organs can be made to elongate after removal from the 
body. 
With regard to the first of these points, it is evident that 
cutting a very narrow tube with thin and sticky walls will 
effectively seal the ends, and that the result of cutting or 
