844 



SCIENCE. 



[N. S. Vol. XIV. No. 361. 



ington, where gardeners have brought the 

 fruit duriug more than twenty years ; but 

 few of them have kept it pure. One may 

 there trace the reversion through various 

 grades from the typical to almost worthless 

 kinds. 



In view of all the facts that have here 

 been stated, there seems to be no room for 

 doubt as to the spontaneous, saltatory and 

 phylogeneticcharacterofthemutation which 

 produced the Washington variety of tomato. 

 Whether it will show the usual degree of 

 varietal stability in future seed propaga- 

 tion, and whether any similar mutation 

 will occur in other varieties of tomato under 

 conditions similar to those of my garden, 

 remain to be demonstrated. 



Charles A. White. 



Smithsonian Institution, 

 October 3, 1901. 



SCIENTIFIC BOOKS. 

 A Treatise on Zoology. Edited by E. Eay Lan- 



KESTER. Part III. The Echinoderma, by F. 



A. Bather, assisted by J. W. Gregory and 



E. S. Goodrich. London, A. and C. Black. 



1900. Pp. vii + 344. 



The student of zoology, if he wishes an ele- 

 mentary text-book, finds as great difficulty in 

 making his selection as he does in buying a new 

 bicycle or typewriter. Apparently the more 

 advanced student will not be thus hampered by 

 any embarrassment of riches, for it is doubtful 

 whether any other work aims as high and at- 

 tains as much as the volume under review. 



The average worker who has added some- 

 what to his primary zoological training finds it 

 a dreary and often fruitless performance to ex- 

 tract the new facts of science or the present 

 state of knowledge on any particular topic from 

 the almost endless collection of ' elementary ' 

 text-books, no matter how valuable they may 

 be in fulfilling their true function. It is almost 

 equally tiresome to sift out the same informa- 

 tion from the great mass of technical papers on 

 particular things. The present volume sup- 

 plies in a large degree this deficiency for the 

 Echinoderma, and is a most welcome addition 



to general zoological literature. The entire 

 series is planned to include ten parts, of which 

 this is the third. Each of the larger groups of 

 animals is to be described by a separate author 

 after a definite model, in order to secure uni- 

 formity in both scope and method. 



The general systematic survey of the phylum 

 Echinoderma, with its seven classes, is quite 

 full and comprehensive and includes the main 

 facts of ontogeny, phylogeny, anatomy and 

 classification. The orders and families are all 

 clearly defined and most of the prominent gen- 

 era are reviewed or mentioned. One of the 

 striking features of this volume is the fulness 

 with which the fossil forms are treated, thus 

 according them their true value in any general 

 treatise on echinoderm morphogeny. Instead 

 of the starfishes and sea-urchins constituting 

 the entire program, or ' whole show,' as they 

 do in the minds of the average student and in 

 half the text-books, here they form but the last 

 two of the seven classes recognized, and the 

 length of their discussion is in proper propor- 

 tion. It is sincerely to be hoped that similar 

 true values will be given among other classes, 

 whether extinct or not. 



The phylum Echinoderma comprises two di- 

 visions or grades, the Pelmatozoa and the Eleu- 

 therozoa. In the first are the classes Cystidea, 

 Blastoidea, Crinoidea and Edrioasteroidea. In 

 the second grade are the Holothuroidea, Steller- 

 oidea and Echinoidea. This arrangement shows 

 the unequal value of the classes and does not ex- 

 press their phylogenetic relations. The latter 

 probably would be more truly represented, ac- 

 cording to Bather, by placing a primitive class, 

 Amphoridea, at the base and deducing from it 

 several lines of descent, namely, Edrioaster- 

 oidea, Anomalocystida, Aporita, Rhombifera 

 and Diploporita. Fi'om the Edrioasteroid line, 

 it is supposed, there sprang first Holothurians, 

 then Stelleroidea, then Echinoidea. The Blas- 

 toids are included in the Diploporite line, and 

 from them as a fresh development with a new 

 lease of life arose the important class Crinoidea, 

 whose discussion occupies, as is wholly proper, 

 nearly one-third of the present volume. 



The class Stelleroidea comprises the Aster- 

 oidea and Ophiui'oidea, generally considered 

 as quite distinct. Some recent genera, how- 



