August 27, 190Et] 



SCIENCE 



285 



these aquatic insects are but little known in 

 this country, and Professor Vorhies has made 

 a good start in describing 18 species that he 

 reared to adult. Six species are considered 

 new. The figures show the structural char- 

 acters of the larvae and also of some of the 

 adults. 



The larvae of gnats of the genus Chirono- 

 mus have often been studied by naturalists, 

 but not the least interesting is a posthumous 

 paper by A. T. Mundy.' The part on the 

 anatomy of the head seems to be particularly 

 well done. There are detailed accounts of the 

 making of the larval tubes, and a summary 

 of the habits of allied Chironomus larva;. 



The largest volume so far published on the 

 " Collections Zoologiques du Baron Edm. de 

 Selys Longchamps " is Fascicle VIII., a mono- 

 graph of the Ascalaphidse' by H. van der 

 Weele. The de Selys collection is particularly 

 rich in this family, possessing many types of 

 Latreille and Eambur. About 200 species are 

 now known, arranged in 50 genera, and the 

 author has had peculiar facilities in studying 

 specimens in many museums and collections. 

 To the two former subfamilies, Schizophthal- 

 minae and Holophthalminse, he adds a new sub- 

 family, Protascalaphinaj, for Stilboptenjx and 

 Albardia. 



In this same series Rene Martin has pub- 

 lished two fascicles (XIX., XX.) on the 

 dragon-flies of the group j3Eschnines, com- 

 pleting the account of this family. There are 

 about 185 species in 28 genera, mostly belong- 

 ing to JEschna or Gynacantha. Many species 

 are described as new, especially from Mr. 

 Martin's collection. Nathan Banks 



SPECIAL ARTICLES 



AN EXPERIMENT IN MUSICAL ESTHETICS 



In the field of psychology, few subjects ofier 

 as many difficulties to the investigator as that 

 of esthetics, and in the realm of esthetics, few 



' " The Anatomy, Habits and Psychology of 

 Chironomus pusio Meigen (the Early Stages)," 

 Leicester, England, 1909, pp. 5G, 8 plates. 



' " Agcalaphiden," Jlonographisch Bearbeitet, 

 326 pp., 254 figs., 2 col. plates, Brussels, 1909. 



topics are more obscure than those that relate 

 to the art of music. 



Problems in musical esthetics, by their very 

 nature, can not be adequately understood 

 without taking account of both their psycho- 

 logical and their purely musical aspects. 

 Unfortunately for the solution of such prob- 

 lems, however, the psychologist and the musi- 

 cian, in too many instances, not only fail to 

 cooperate in their studies, but even lack an 

 appreciative and sympathetic understanding 

 of each other's methods and conclusions. 

 We are much in need of two-handed men, 

 equipped in both directions — or else, of inti- 

 mate collaboration between the investigators 

 in the separate fields. 



Largely because of a lack of just such col- 

 laboration, the subject of musical dissonance 

 has been invested with an atmosphere of un- 

 certainty and confusion, in the minds of 

 both psychologists, estheticians and musicians. 

 The difficulties inhere, particularly, in am- 

 biguous definitions of the word dissonance 

 itself — definitions to which we have become 

 so accustomed that, as a rule, we fail to notice 

 their inadequacy. Among various uncertain 

 and shifting meanings assigned to the term, 

 two fairly defined conceptions present them- 

 selves: (1) a dissonance is a combination of 

 simultaneous tones that sounds harsh; (2) a 

 dissonance is a combination of simultaneous 

 tones that requires resolution (i. e., creates a 

 feeling of unrest, removable only when the 

 given combination of tones is followed by a 

 more or less prescribed other combination). 

 Either of these definitions is feasible and ade- 

 quate, in itself; the confusion arises from the 

 fact that, even among men usually careful of 

 their terminology, the word dissonance is em- 

 ployed, first in the one sense and then in the 

 other. 



It seems to the present writer that the term 

 dissonance will be both more nearly exact in 

 its meaning, and more useful to the musician, 

 if it be defined, simply, as a combination of 

 simultaneous tones that sounds harsh (psy- 

 chologically, the sensation produced by such 

 a combination). Under the terms of this defi- 

 nition, the only dissonant intervals are those 

 known as seconds and sevenths; and the only 



