An aboral vessel embraces the sense-organ, but has no external opening.
The mouth is midway in its length and is opposite the sense-organ or eye-spot.
But whatever might be the advantage or disadvantage of such a sense-organ, we as yet do not possess one.
Two crescentic rows of ciliated papillae lie in the transverse plane on each side of the sense-organ.
This is due to the excitation in the sense-organ continuing after the object has ceased to affect it.
Now it is led to undertake, so to speak, the work of a sense-organ of a higher grade.
And the higher the sense-organ the more directly and purely does it minister to consciousness.
These bodies have been compared to a Pacinian body (a sense-organ found in Vertebrates) and they bear no little resemblance to it.
sense organ n.
A specialized organ or structure, such as the eye, ear, tongue, nose, or skin, where sensory neurons are concentrated and which functions as a receptor. Also called sensor.