610 CORAL. 



Their studies, especially those of Peyssonel, led them to consider it 

 as an animal. Having- taken coral recently gathered, they put it in a 

 basin filled with sea water and examined it with care. The arbores- 

 cent stone was covered with a softer flesh, likewise colored red, and on 

 that flesh were living numerous animalcula; provided with movable 

 tentacles. These creatures really formed a part of the flesh which 

 ensheathes the stone, producing it as the organism of man}' animals 

 produce the mineral substance of their shell or their skeleton. Peys- 

 sonel thus corrected one of the most serious errors of natursd history. 

 He not only placed in its true position an important group of marine 

 creatures, but also corrected a mistaken view which had led to search 

 in the wrong field for connecting links between the two great kingdoms 

 of nature. 



These investigations were so searching and thorough that an entire 

 century passed before much was added to this discovery. It was 

 about the middle of the last centur}' that our knowledge of coral was 

 increased b}^ new acquisitions derived from the patient and persevering 

 studies of an eminent French zoologist, H. de Lacaze-Duthiers, who 

 has just left us after a life devoted wholl}' to science. From that time 

 coral was understood. 



The red stone is nothing less than the skeleton produced hy minute 

 animals, and serving for their support. Thanks to it they lift them- 

 selves above the rock to which this skeleton is attached, and maintain 

 themselves erect in the water which surrounds them. This skeleton 

 is arborescent, and its tree- like appearance gave rise to the ancient 

 error concerning its nature. It has a trunk fixed on a solid support 

 and knotted branches that extend in ever}" direction. It is sometimes 

 several feet in height and the thickness of its principal branches may 

 be half an inch or more. Each trunk and branch carries, scattered 

 over its surface, some millimeters apart, arranged without any 

 apparent order, animals similar to each other, having the structure 

 that characterizes the group of polyps. The bases of these creatures 

 enlarge, thicken, and unite, forming by this union a sheet that sur- 

 rounds the skeleton like a sheath, enveloping it wholly, following all 

 its branches and nodosities. Together with the polyps, this is the 

 living and fleshy portion, the "sarcosome" of the collection. Its 

 internal surface is closely applied to the stony skeleton to which it 

 gives origin; it produces it and continually secretes new la,}"ers in 

 addition to those alrcnidy existing. These laj^errf are made of calcareous 

 matter colored ]-ed by a special substance; the sarcosome secretes 

 them as the mantle of a mollusk produces the shell that protects the 

 animal. 



The structui'c of each ])olyp is \'ery simple. It is from 8 to 4 mm. 

 in height and 2 to 8 mm. in diameter. Withdrawing at the slightest 



