80 



SCIENCE. 



[N. S. Vol. XVIII. No. 446. 



Let us as teachers accept no single ele- 

 ment or variety of culture as the one es- 

 sential ; let us remember that the best fruits 

 of real culture are an open mind, broad 

 sympathies and respect for all the diverse 

 achievements of the human intellect at 

 whatever stage of development they may 

 be to-day— the stage of fresh discovery, or 

 bold exploration, or complete conquest. The 

 moral elements of the new education are 

 so strong that the new forms of culture 

 are likely to prove themselves quite as 

 productive of morality, high-mindedness 

 and idealism as the old. 



Chas. "VY. Eliot. 



SCIENTIFIC BOOKS. 

 West Indian Madreporarian Polyps. By J. E. 

 DuERDEN. Memoirs of the National Acad- 

 emy of Sciences, Vol. VIH. 1902. 

 It may seem strange that notwithstanding 

 the thorough study that has been devoted to 

 the skeleton of the corals our knowledge of 

 their soft parts has been exceedingly limited 

 until recent years. It must be remembered, 

 however, that interest in the anatomy of 

 the nearly related Actiniaria was not really 

 awakened until the publication of Eichard 

 Hertwig's report on the Challenger collection 

 in 1882, and the technical difficulties in the 

 way of extended anatomical study of the coral 

 may well be advanced as an excuse for its 

 neglect. 



In the same year that Hertwig's report ap- 

 peared, however, von Koch laid the foundation 

 for a proper appreciation of the significance 

 of the soft parts of the corals by demonstrating 

 the ectodermal nature of the corallum, and 

 since that date valuable contributions to the 

 anatomy of the Madreporarian polyps have 

 been made by von Koch himself and by 

 Bourne, Fowler and von Heider. The total 

 number of forms studied has, however, re- 

 mained comparatively small, and although 

 enough information was gained to demon- 

 strate a close similarity of the Madrepores to 

 the Hexactinise, yet there was a lack of suffi- 



cient data upon which general conclusions 

 could be based. A systematic study of a 

 large number of forms was needed, and this 

 need has recently been supplied by Dr. J. E. 

 Duerden in his paper on the West Indian 

 corals, a paper destined to stand as a land- 

 mark in our knowledge of Madreporarian 

 morphology equal in importance to that es- 

 tablished by von Koch. 



Duerden has made a thorough study of the 

 morphology of no less than twenty-six species 

 of corals belonging to nineteen different 

 genera, and, when the difficulties in the way 

 of such work are properly appreciated, nothing 

 but admiration can be expressed for the 

 patience, perseverance and thoroughness evi- 

 denced in every page of his work. It is 

 monographic in its nature, considering in de- 

 tail the structure, histology and development 

 of the coral polyps as a group, and concluding 

 with full descriptions of the special mor- 

 phology of the various forms studied. 



Dr. Duerden gives good reason for believ- 

 ing that all corals are fundamentally hexam- 

 erous, the corallum septa making their ap- 

 pearance symmetrically in embryos already 

 provided with the six pairs of primary mesen- 

 teries. In some species the hexamerism be- 

 comes much obscured in later stages, while 

 in others it is more or less distinctly pre- 

 served; and it has been possible to correlate 

 these differences with the mode of non-sexual 

 reproduction followed by the species. Two 

 principal methods of non-sexual reproduction 

 are recognizable, namely, gemmation and 

 fission. In the former method the mesenteries 

 of the new individual are formed de novo 

 and repeat the embryological development, and 

 consequently the hexamerism of those of the 

 parent, while in the latter method half the 

 mesenteries of the parent pass directly to each 

 descendant whose growth processes are limited 

 to an attempt to reproduce the lacking parts, 

 a second fission frequently supervening before 

 the attempt is carried to completion. In the 

 polyps produced by gemmation the mesen- 

 teries present the usual hexamerous arrange- 

 ment, two pairs of directives and at least four 

 additional pairs arranged symmetrically to the 



