THE ROLE OF MUCUS IN CORALS. 597 
Should the fragment of meat be large or too heavy for the 
stomodzal current alone to set it in motion, its transference 
is assisted by negatively thigmotactic reactions on the part 
of the disc and tentacles. In a general way these may be 
understood by saying that the depressed parts of the dise 
and tentacles immediately under the fragment attempt to 
recover and elevate themselves, and, in so doing, displace 
the object resting upon them, causing it to move feebly one 
way or another. In the meantime the food has become 
entangled in mucus, and, as this is being drawn towards the 
mouth, it generally happens that the first movements of the 
meat are also mouthwards, and, once a definite transference 
towards the mouth is set up, it usually continues uninter- 
ruptedly, the force of the incurrent becoming greater the 
nearer the approach to the mouth. In like manner any 
object, nutritive or otherwise, resting upon the disc is 
ingested once it becomes entangled in the inflowing mucus 
altogether independent of its nutritive value. On account of 
their smallness the tentacles in Fungia are found to be of 
very little importance in transferring food to the mouth, 
though in other corals and actinians this is one of their 
principal functions. 
In the feeding experiments it was frequently demonstrated 
that it is not the food itself which brings about the reversal 
of the stomodzal current and accompanying reactions, but 
the extractives from it, and further, that these must reach 
the mouth or its immediate neighbourhood. Often small 
fragments of meat or crab’s muscle were placed on the 
marginal parts of the disc without calling forth any responses 
on the part of the mouth or changing the direction of the 
stomodeal current; the juices diffusing from them evidently 
failed to reach the lips, and no reaction followed. The 
particles of food in this case were ultimately wafted from the 
dise by the ordinary outward current in the same manner 
as non-nutritive substances. If, however, the meat were 
brought nearer the mouth the latter opened more widely, a 
positive current was established, and ingestion took place. 
von. 49, PART 4,—NEW SERIES. 4A 
