302 
GEORGE RALPH MINES. 
ligaturing will be the same. As Barthels remarks, the tubes 
produced under these conditions are thinner than normal and 
the elongation takes place more slowly. 
I find that if the ligature is tightened around their bases 
as quickly as possible after the appearance of the Cuvierian 
organs outside the animal, the organs do not shoot through 
the water to auything like the normal extent, but fall in coils 
close to the animal. If the ligature is tied somewhat later, 
the elongation of the organs continues in a fashion more 
resembling the normal, but it is still imperfect. As the 
elongation of the distal part of the tube proceeds, the 
proximal part, which was distended before the ligature was 
tied, is seen to shrink. This shrinkage does not occur in a 
normal uninterrupted discharge. 
Fig. 1a shows a normal discharge of five Cuvierian organs. 
Fig. 1b shows a second discharge from the same animal^ 
where the tubes were ligatured very shortly after ejection, by 
tightening a loop of silk placed close outside the anus through 
which the organs passed. 
In order to display the Cuvierian organs the specimens were 
photographed in a black dish filled with sea-water. The 
animal is not seen, therefore, owing to its deep pigmentation. 
Fig. 2 gives a closer view of some Cuvierian organs tied at 
their bases shortly after discharge; it shows the beaded 
appearance often presented by the tubes under these con- 
ditions. 
Fig. 3 represents a group of undischarged Cuvierian organs 
taken from the body-cavity of Holothuria nigra. 
Fig. 4 shows a few of these organs in a shallow dish, some of 
them being pulled out. Picking up an undischarged organ at its 
ends, it is easy to pull it out to a great length, but the resulting 
thread looks wholly unlike the tube as normally discharged, 
in that it is thin and not transparent. When an organ is thus 
in part pulled out, the remaining portion often undergoes some 
elongation, the thin thread produced coiling and lying at the 
bottom of the vessel. The extent to which this goes on 
varies considerably in different cases ; it seems to depend 
