June, '09] JOURNAL OF ECONOMIC ENTOMOLOGY 225 



between the sense organs (receptors), the central nervous system and 

 the muscles or glands ( effectors ). Among the most intangible phe- 

 nomena that we have to deal with are sensations, yet the old classifi- 

 cation of sense organs is based on such internal conditions, and conse- 

 quently the usual classification, that of sight, smell, touch, hearing 

 and taste is quite unsatisfactory'. Because of the inadequacy of the 

 subjective basis for classification, the tendency is to transfer the 

 treatment to an objective basis. ^ The external world forms a basis 

 for the source of stimuli or energy change. On this basis sense organs 

 are grouped into only two general classes, viz. : 1. Sense organs stimu- 

 lated by ether changes, such as light, heat and electricity. 2. Sense 

 organs stimulated by material changes, sub-divided into two sub- 

 classes : (a) Physical, organs which receive prolonged contact stimu- 

 lation, such as touch and pressure, and organs which receive vibratory 

 contact, commonly called sound organs (hearing) ; (h) Chemical, or- 

 gans which serve as receptors of chemical stimuli, taste and smell. 



Thus the weight is thrown on the external world, we are not limited 

 to sensations, and, what is most important, a basis for measurement 

 may be secured, — e. g., light intensity can be measured in terms of can- 

 dle meters and can be controlled; chemical solutions can be measured 

 in degrees of concentration and can be controlled. And here is where 

 the great difference exists between earlier and more recent work in 

 animal behavior. Accuracy of measurement is the great criterion by 

 which modern work is judged, and this involves not only a knowledge 

 of zoology or entomology and their histological methods, but also a 

 knowledge of the physics and chemistry of the stimulus employed. 

 The following extract taken from the editorial notes of a recent num- 

 ber of the Experiment Station Eecord- is quite apropos at this time : 



' ' The advantage of agricultural science over the individual sciences 

 as applied to agricultural problems should lie in its special point of 

 view and in the bringing of various sciences to bear on these problems. 

 For its purposes the boundaries of the primary sciences are over- 

 stepped. The investigator in that field is not restricted to a single 

 science, but employs the teachings and the methods of several, as his 

 case requires, acting as a connecting or coordinating agent. This cos- 

 mopolitan relationship calls for widespread familiarity with the whole 

 field of natural science. Its danger is too close specialization and dis- 

 regard of everything in the pure sciences which does not bear directly 

 and quite immediately on the field of agriculture. Such a course 

 tends to narrowness and to superficiality on the part of its adherents." 



