THE AMERICAN 



MONTHLY 



MICROSCOPICAL JOURNAL 



YOL. III. 



N^EW York, December, 1882. 



]S^o. 12. 



Coral in an Aquarium.* 



BY W. E. DAMON. 



I have had several varieties of liv- 

 ing coral, including Astrangia, Ocac- 

 Itna, Porites, Meatidrina, etc., grow- 

 ing in my marine aquarium ; only 

 the first of which I shall speak of in 

 this paper. 



1 have watched it for hours and 

 days at a time with the greatest de- 

 light, and I used to think that no 

 well-regulated family should try to 

 exist without a specimen of live cor- 

 al ; but that may be an exaggerated 

 idea of the subject, and I have learned 

 to conceive how this may be possible. 

 The beauty of a fine zoothome (that 

 is, a number of coral polyps on a 

 branch of coral), fully expanded and 

 searching for their food, is almost in- 

 describable — a branch of the most 

 exquisite flowers, a living royal bou- 

 quet ; to the naked eye, in fact, what 

 some of those beautiful minute ob- 

 jects, which your Society have so 

 kindly shown to me from time to 

 time under the microscope, seem to 

 you, and that, I'm sure, is pretty 

 enough ! My first specimen, Astran- 

 gia, as described by Dana, was about 

 as large as the palm of the hand, en- 

 crusting an uneven surface of stone 

 in nodular shape. When the polyps 

 were all out of their calicle, the 

 zoothome, or animal part, with long, 

 slender, thread-like, fleecy tentacles, 

 dotted all over with little knot-like 

 markings, extended in all directions 

 in search of food. Some of the po- 

 lyps were nearly an inch in height 

 above their calicle, and in diameter 



* Read before the New York Microscopical 

 Society, November 17th. 



nearly as large as a pipe stem, the 

 mouth situated in the centre of the 

 tentacles, as in the actinse. In feed- 

 ing them with pieces of clam, oyster, 

 chicken, or raw beef, I sometimes 

 hand to each individual a piece sepa- 

 rately, but generally cut it up in small 

 pieces, in size from the head of a pin 

 to a grain of wheat, and drop them 

 into the water directly over the po- 

 lyps, when every piece is securely 

 seized by their outstretched arms, 

 passed along slowly but surely to the 

 mouth, and swallowed. All of this 

 can be plainly seen through their 

 semi-transparent, glassy walls. After 

 digestion has taken place the animal 

 sinks down in its calicle to rest. 



These long, fairy-like tentacles, 

 implements for gathering food, how- 

 ever, are not the innocent objects 

 they seem to be, as many an unlucky 

 shrimp or crab can testify, for each 

 one of them carries concealed in the 

 little knot-like protuberances already 

 mentioned, a perfect armory of wea- 

 pons of warfare called lasso threads, 

 with which they shoot out their pois- 

 oned arrows. 



I have seen a poor shrimp acci- 

 dentally pass too near one of these 

 groups when he would receive such 

 a shock as to make him jump clear 

 out of the tank and fall upon the 

 floor — and others that would curl up 

 in a trembling sort of way, turn 

 white and die. 



An association of these polyps 

 must be of a most intimate kind ; 

 though each individual has a separate 

 mouth, tentacles and stomach, the 

 intervening tissue which connects 

 them is subject to a free circulation. 

 Their principal business, however, is 



