April 5, 1918] 



SCIENCE 



345 



are not yet back to their former bad condition. 

 Maynard M. Metcalf 

 The Orchard Laboratory, 

 Oberlin, Ohio 



SYSTEMATISTS AND GENERAL BIOLOGISTS 



May I endorse the suggestion by Dr. L. O. 

 Howard?^ He says that he does not know 

 whether determination of species is important 

 to the experimental embryologist. When, as 

 zoological recorder for Eehinoderma, it was 

 my duty to read a large number of papers by 

 those workers, I formed the opinion that it cer- 

 tainly was important, and wrote :^ 



It is well to urge on those gentlemen the need 

 for an accurate determination of the material 

 with which they work. They are too much inclined 

 to infer the universal from the particular, and to 

 overlook the fact that species and even local races 

 differ from one another in their reproduction and 

 development, just as much as in their habits and 

 perhaps more than in their structure. 



This plea was strongly supported by Vigu- 

 ier.3 



Accurate discrimination of species is no less 

 necessary for the field naturalist. J. H. Fabre, 

 always ready to gird at the museum worker, 

 had to confess that he had confused under the 

 one name Eumenes pomiformis three species 

 of mason-wasps, so that it was not possible for 

 him " to ascribe to each of them its respect- 

 ive nest" (I quote from the selection just 

 published under the title " The "Wonders of 

 Instinct," London, Fisher Unwin). 



Most geologists have by this time learned 

 that, for lack of the precautions advocated by 

 Dr. Howard, many of their fossil lists are not 

 worth the paper they are printed on. Recent 

 advances in stratigraphical geology are almost 

 entirely due to the keener appreciation of mi- 

 nute specific differences. 



In a word, every kind of biologist should 

 find in the despised taxonomist a valuable, in- 

 deed an indispensable, ally; and in our mu- 

 seums he should recognize a depository where 

 the evidence for his conclusions may be pre- 

 served for future generations of workers. 



London F. A. B.\ther 



iZool. Sec, for 1901. 



1 Science, January 25, p. 93. 



> 1903. Ann. Set. Nat. Zool, ser. 8, Vol. 17, p. 71. 



SCIENTIFIC BOOKS 

 Lectures on Heredity. By H. S. Jennings, 

 Ph.D., LL.D., Johns Hopkins University; 

 Oscar Riddle, Ph.D., Department of Ex- 

 perimental Evolution, Carnegie Institution; 

 and W. E. Castle, Ph.D., Harvard Univer- 

 sity. Delivered under the auspices of the 

 "Washington Academy of Sciences, "Wash- 

 ington, D. C. 1917. Pp. 82. Bound in 

 buckram, 50 cents. 



This is the second annual series of lectures 

 presented before the "Washington Academy of 

 Sciences and reprinted in collected form from 

 the Journal of that academy. 



The study of genetics has become so highly 

 specialized that workers in the different fields 

 have ceased, except in rare instances, to make 

 a serious effort to coordinate their work with 

 that of others. 



Dr. Jennings's classical work on the nature 

 of variations in lower organisms deals with 

 one of these highly specialized branches, and 

 students of other branches should appreciate 

 the service rendered by Dr. Jennings in his 

 painstaking comparison. 



" Having satisfied myself as to the nature of 

 the variations that arise in the creatures that 

 I have studied, I have looked about to see 

 what other workers have found; and to deter- 

 mine whether any unified picture of the mat- 

 ter can be made." 



After claiming that the idea of genotypes 

 must be admitted as a general condition, the 

 author concludes that this result " is not 

 final, that it does not proceed to the end." 



In a uniparental organism, from which all 

 question of the recombination of existing di- 

 versities is eliminated. Dr. Jennings finds 

 that " the immense majority of the hereditary 

 variations were minute gradations. Variation 

 is as continuous as can be detected." 



The points at issue between the " genotypic 

 mutationists " and the upholders of gradual 

 change are clearly and concisely stated. Set- 

 ting aside the question whether the evidence 

 held to support the gradual change theory is 

 conclusive or not, he proceeds directly into 

 territory of the mutationists and shows that 

 the " multiple allelomorphs " found in Droso- 



