438 'Journal of Comparative Neurology and Psychology. 



nal behavior and other physiological processes. Just as functions 

 become localized in organs and become more definite, as well as 

 susceptible of analysis, so in behavior increasing definiteness and 

 specialization of functions in separate forms of activity are met 

 with in the ascending scale of animal life. 



CLASSIFICATION AND DESCRIPTION OF MOVEMENTS. 



In classifying the activities of the Corethra larvae we recognize, 

 in addition to the ordinary kind, the occurrence of automatic 

 movements due to alteration of specific gravity, by means of the 

 air sacs. Observation of the muscular movements leads to clas- 

 sifying them in several groups according to their form: (i) locomo- 

 tion, (2) food-taking, (3) convulsive wrigglings which have the 

 appearance of spontaneous overflows of energy, (4) cleaning move- 

 ments. The muscular movements are all produced by the lash- 

 ing of the body, which is destitute of locomotor appendages except 

 a ventral, caudal fin composed of a row of bristles. 



Each separate movement is effected by a single lashing motion 

 of the body and is followed by an interval of rest. Under a certain 

 condition of stimulation, to be considered later, they may move 

 continuously for a short time. Occasionally under ordinary con- 

 ditions a movement is followed in close succession by a second, 

 rarely by a third. In a hundred successive movements, frequently 

 a third of them occur in twos. 



Another characteristic of the locomotion is a lack of symmetry. 

 After a movement the larva is found at a little distance pointing 

 in a new direction. In a recorded series it is found to point suc- 

 cessively in all directions (Fig. 3). In rapid flight, under the con- 

 dition of stimulation which causes continuous motion, they move 

 in a fairly straight, but zigzag path. 



Still another general quality of the movements is their energetic 

 character. Each one starts from rest and lack of momentum is 

 compensated by the energy put forth. One half of the muscula- 

 ture is ordinarly involved. Fatigue may be readily produced by 

 mechanical stimulation. 



The movements at times acquire a degree of regularity, most 

 pronounced in the active state of the animal. An observed case 

 of unusually high frequency may be instanced, in which the num- 

 ber of movements per minute for ten consecutive minutes was 



21, 21, 20, 21, 22, 22, 22, 20, 19, 23. 



