A similar animal caught on the 20th November 1837, in south latitude 25 degrees 12 minutes; east longitude 106 degrees 49 minutes, emitted a violet-coloured dye.

The emission of this evidently depends upon their being irritated, as I found by many experiments.
The method in which this animal fills its float is curious, it throws it back, and gradually lifts the lip of the valve out of water, until the valve stands vertical, it then closes the valve tightly round a globule of air, around which it folds, by means of the most complex and delicate machinery.

The valve is then bent over until it touches the edge of the float nearest the head, and when it is in this position, the portion of it which is inflated with air looks like a bladder, the air gradually is expelled into the float, and as this process takes place the bladder in the valve diminishes, and the valve becomes by degrees like a lip pushed forwards until it lies flat on the float.

The valve is composed of two portions, a cup and a lip.

The time occupied from first removing the valve from the float, until the inflation, and the expulsion of air into the float being completed, so that the valve begins to move again, is 61 seconds, from the mean of several experiments.
These animals have also the power of compressing the valve into a hollow tube, which they elevate above the water like a funnel, and draw down air through it.
The colouring matter which they emit has no stinging, electric or deleterious properties whatever, that I could discover.