rEBRUART 6, 1920] 



SCIENCE 



143 



the numerous diagrams which accompany the 

 text. 



In a brief review such as the present it is 

 not possible to do justice even to some of 

 the more important details of Crampton's 

 masterly work, but it is interesting to see that 

 according to^ Garrett, Partula clara was rare 

 and fotrnd only in a sector of valleys com- 

 prising about 1/4 the area of Tahiti, while 

 Crampton found it to be very common and to 

 range over 4/5 of the whole island, this dis- 

 persal having been accomplished by migration 

 fromi the former restricted habitat of the 

 species. There are now 1 subspecies, and 

 mutation has occurred not only in some of 

 the new valleys the snail has occupied since 

 Garrett's time but also in the area in which 

 it was found by Garrett. 



Partula nodosa which in 1861 was confined 

 to Punaruu valley has now migrated into 6 

 other valleys, and 3 new varieties have arisen 

 in the area into which it has traveled, as 

 Crampton illustrates in his test-figure 6 on 

 page III. 



Nearly one half of Crampton's volume is 

 devoted to an analysis of the group species 

 Partula otaheitana with its 8 subspecies and 

 varieties of primary, secondary, and tertiary 

 degree, thus constituting the most complex of 

 the known species of Partula. 



Crampton collected more than 20,000 adult 

 and 6,000 adolescent snails of this form in 

 practically every habitable area of Tahiti. 



In Fautaua valley these snails form an 

 extremely complex colony which stands in 

 parental relation to the diverse colonies of 

 other valleys; for in any one of the latter the 

 shells exhibit one combination or another of 

 the so-called unit characters displayed by the 

 Fautaua gi-oup as a whole. In this snail 

 Crampton finds some evidence that in the 

 variety ruhescens red and yellow colorations 

 bear a Mendelian relation to one another, red 

 being dominant. On the other hand in the 

 variety affinis plain color seems to be domi- 

 nant over the banded pattern in Mendelian 

 inheritance. 



Partula hyalina is peculiar in not being 

 confined to Tahiti for it is found also in 

 Mangaia, and Moki of the Cook Group and 



Kurutu and Tubuai of the Austral Islands, 

 and in marked contrast to this wide dispersal 

 Partula, filosa, is found only in Pirai, and 

 P. producta in Faarahi valley and have not 

 migrated from these valleys since Garretfs 

 time. 



Crampton concludes that in the production 

 of new varieties the originative influence of 

 environment seems to be little or nothing, and 

 isolation is a mere condition and not a factor 

 in the differentiation of new forms. This is 

 in accord with the studies of Bartsch upon 

 Cerion, for he found that no new varieties 

 were produced in any of the numerous 

 colonies of Bahama Cerions which he estab- 

 lished upon the Florida Keys from Eagged 

 Keys near Miami to Tortugas. When how- 

 ever, these Cerions of Bahaman ancestry 

 crossed with the native Florida from the 

 second generation of the hybrids gave rise to 

 a large number of variations both in form 

 and color. 



This observation indicates that similar ex- 

 periments should be conducted upon Partula, 

 for it seems possible that new species may 

 result from the breeding of mutations with 

 the parent stock, or of species with species 

 producing fertile hybrids unlike either of the 

 parent stocks. 



The editorial work upon Crampton's volume 

 reflects the greatest credit upon Mr. William 

 Bamtun the well known editor of all publica- 

 tions of the Carnegie Institution of Washing- 

 ton. The 15 colored plates lithogTaphed by 

 Hoen are faithful reproductions of the colors 

 and appearance of these snails, and the fact 

 that the book is published upon the best of 

 paper is fortunate for it will be even more 

 interesting to students a hundred years hence 

 than it is at present. 



Crampton's work is of such wide interest 

 and importance, and in the light of Bartsch's 

 observations so suggestive of future experi- 

 mental research that it is hoped these studies 

 may be pursued continuously under the 

 auspices of the Carnegie Institution until 

 final conclusions have been reached through 

 breeding experiments conducted in the field. 



A. G. M. 



