190 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1917. 



Peysonnel announced the results of his laborious investigations in the 

 West Indies, and even after his observations were published in 175;}, 

 a few perverse individuals continued to adhere to the old views. It 

 now seems strange that Peysonnel's researches constituted one of 

 the important advances in our knowledge of the animal kingdom. 



Of the early savants, Patrick Brown in his "Civil and Natural 

 History of Jamaica," 1756, Seba in his " Locupletissimi rerun natu- 

 ralium Thesauri accurata descriptio," 1758, Knorr in his "Deliciae 

 selectae naturae," 1771, and many others described and figured many 

 corals; and much pleasure may be derived from the text and the care- 

 fully executed figures of these authors. One of the most delightful 

 of story-tellers and lyric poets, Adelbert de Chamisso, exiled from 

 France as a result of the French Revolution and a refugee in Ger- 

 many, was one of the early contributors to coral-reef theories. He 

 described one species of stony coral and published exquisite figures of 

 it based on his own drawings. Though the enthusiasm of many of 

 the early writers on this subject is inspiring and their charm is great 

 and though the temptation is strong to yield to their spell and con- 

 sider the subject only as they so fascinatingly present it, attention 

 must be diverted from them and directed toward the objects them- 

 selves. 



WHAT aim: corals? 



Since the days of Peysonnel all informed students, except the few 

 perverse individuals to whom allusion has been made, have believed 

 that corals are not merely animals but that they are animals closely 

 akin to the sea anemones. Like sea anemones, they are, at least while 

 young, more or less cylindrical in form; the lower end, called the 

 foot, is attached to some object; around the margin of the flattish 

 upper end there are tentacles that can be extended or retracted ; and 

 near the middle of a flattish area within the tentacles there is a slit- 

 like mouth that can be widely opened or closely shut. Below the 

 fleshy floor between the tentacles and the mouth there are folds of soft 

 tissue, known as mesenteries, that are attached to the wall on their 

 outer ends, but on their inner ends they are free below a rathei 

 short tube, called the gullet or esophagus. On the edges of the mes- 

 enteries there are often curled filaments, called mesenterial fila- 

 ments. Figures 1 and 2 on plate 1 are illustrations of two Blaschka 

 glass models of sea anemones. 



One of the peculiarities of corals and related animals is that the 

 outer surface of the animal tissue, including the tentacles and the 

 mesenterial filaments, are beset with lasso stinging-cells (see text fig. 

 4, p. 207), each of which may shoot out a small dartlike object that at 

 one end is attached by a thread. Another peculiarity is that their outer 

 surface secretes slimy mucus ; and a third attribute is that their sur- 



