March 30, 1906.] 



SCIENCE. 



497 



tribes of that continent, and in this way it 

 proved to be a very valuable demonstration 

 in comparative ethnology. 



Alfred C. Haddon. 



SCIENTIFIC BOOKS. 

 The Coral Siderastrea radians and its Post- 

 larval Development. By J. E. Duerden. 

 Washington, U. S. A. Published by the 

 Carnegie Institution. December, 1904. Pp. 

 130, with 11 plates. 



This handsome Carnegie memoir contains 

 the record of an investigation begun at the 

 Institute of Jamaica and subsequently car- 

 ried on at the Johns Hopkins University and 

 the American Museum of Natural History 

 in New York. The author's prolonged resi- 

 dence in the West Indies gave him unusual 

 opportunities in the way of command over 

 living material, and the memoir makes valu- 

 able additions to our knowledge on many 

 points of coral morphology. 



An introduction deals with the systematic 

 zoology and the habits of the species which is 

 abundant and accessible in Kingston harbor. 

 The form is obviously one of those convenient 

 hardy types destined to play a part in labora- 

 tory investigations of histological and physi- 

 ological character. Both the adult colony 

 and the young polyp after metamorphosis 

 grow in confinement and may be hand-fed. 

 There follows an ample description of the 

 anatomy of the adult. The species, like other 

 West Indian corals, is possibly protogynous, 

 although Professor Duerden calls to mind that 

 Gardiner has established the converse phe- 

 nomenon, protandry for Flabellum. Duer- 

 den takes up the question as to the way in 

 which the coral skeleton, as a product of cel- 

 lular activity, is produced. He confirms Miss 

 Ogilvie's observation that the corallum can 

 be seen in favorable parts of the adult and 

 young polyps to be composed of minute skel- 

 etal units of a polygonal shape and exhibiting 

 a fibro-erystalline structure. But whereas 

 Miss Ogilvie interpreted these bodies as actual 

 cells which were produced through the pro- 

 liferation of the ectoderm, becoming calcified 

 as fast as produced, Duerden regards them 



as secretory products which are laid down 

 wholly external to the ectodermal cells. In 

 support of this view, essentially that advanced 

 by von Koch, Duerden finds that the layer of 

 ectoderm concerned in the production of the 

 skeleton is always a simple layer, and that, 

 moreover, it is always separated from the 

 corallum by a homogeneous mesogloea-like 

 stratum. It is in this stratum of homogene- 

 ous matrix that the author believes the cal- 

 careous crystals forming the skeleton are first 

 deposited. 



A third section deals with the post-larval 

 development. The larvae, of the usual coral 

 type, were obtained in July, and were kept 

 under continuous observation for some months 

 after attachment. Many valuable facts con- 

 cerning the succession of the tentacles, mesen- 

 teries and various parts of the corallum are 

 recorded in this section. A feature of in- 

 terest lies in the attention paid to individual 

 polyps. The partial transparency of the 

 young animal permits of instructive views 

 during life, and thus in one and the same 

 individual the correlated development of the 

 various organs could be followed from day to 

 day. A result of this method was that periods 

 of rapid growth and relative rest could be 

 distinguished. The author points out that a 

 phylogenetic significance possibly attaches to 

 some of the more persistent stages, such as, 

 for instance, that in which complete pairs of 

 mesenteries (directives) are found at the two 

 ends of the oesophagus, with two pairs, each 

 consisting of a long (complete) mesentery 

 and a short one, on each side of the oesophagus. 

 This condition continued unchanged for a 

 period varying from three weeks to three 

 months. The author's theoretical views as to 

 the meaning of this particular stage are 

 summed up as follows: 



The long retention of freedom of the fifth and 

 sixth pairs of protocnemes suggests to my mind 

 an ancestry in which the mesenteries as a whole, 

 including the metaenemes, were alternately long 

 and short, excluding, of course, the axial directives. 

 Among modern examples this is retained in the 

 mesenterial system of the zoanthids, Porites, and 

 Madi-epora, and was perhaps characteristic of 

 the Rugosa. 



