224 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
be formed by regeneration. That the madreporic plate is not essential to tbe life of 
the star, at least for a very long time, is shown by another experiment: This organ 
was removed from five large stars on June 14, and on November 5 one of them was 
alive and healthy, but had not regenerated the lost structure. The madreporic plate 
was wanting in a specimen caught at Woods Hole on April 4. Another was taken 
which had an accessory madreporic plate, which was not, however, connected with the 
stone canal. In the last report I mentioned an experiment in which this body was 
extirpated and regenerated before the end of the season. 
In every known case of regenerating star-fish caught on the mops and dredges 
the new growth is limited to the arms. The arms are readily loosened and cast off 
when injured, but almost certainly do not produce new stars, as is shown by the 
experiment in which single arms have been kept three months without trace of 
regenerating, and by the fact that single arms regenerating the rest of the stars have 
never been found among this species of star (they are common in some foreign species). 
Star-fish which have been cut in two behave differently in different cases. They may 
live for a long time without regenerating the remaining arms to the slightest degree; 
they may show no sign of regeneration for several weeks and then regenerate one or 
more arms; they may soon regenerate only one or two of the arms when three are 
required to complete the original form of the body. The rate of regeneration and 
perhaps the possibility of regeneration are, like the rate of growth, dependent on the 
food supply. It is probably possible for two or more complete stars to result from one, 
but in many experiments in which the stars were carefully protected this result has not 
been obtained by me. The probability of this result occurring when stars are torn 
apart and thrown overboard is doubtless very slight, for, as the experiments show, such 
stars have difficulty in obtaining food and are especially liable to injury and to destruc 
tion by other stars or enemies of various kinds. 
XV. What are the artificial methods of destruction now in use in Rhode Island or 
elsewhere f 
Star-fishes are caught in considerable numbers with the spear and tongs, but the 
more efficient method is the use of the “ tangle” or “ mop.” The tangle consists of a 
number of mops of cotton waste or similar material attached to an iron bar. By 
dragging these mops over the oyster-beds the stars become entangled and are drawn 
up with the mops. The mops are usually detached from the iron bar and are thrown, 
together with the stars, into a tub of hot water. Meanwhile other mops are attached 
to the bar and thrown overboard. After the stars are killed they can be more easily 
picked off the mops than when they are alive. Some oystermen prefer to dredge up 
oysters, stars and all, and, after having culled out the stars, to replant the oysters. 
The star fish become easily entangled in the mops, not only because they are 
rigid and covered with spines, but because the little forceps (pedicellaria) thickly 
scattered over the surface of the body catch hold of the threads of the mop. If one 
presses the upper surface of a live star-fish against the back of his hand he will 
find that these pedicellaria grasp the hairs on the hand tightly and will sustain 
the whole weight of the star- fish. 
