388 KANSAS ACADEMY OF SCIENCE. 



the physiological method : Place a small quantity of acidulated water 

 in a vessel, a bit of mercury, and a crystal of bichromate of potash. 

 In a moment the mercury becomes the seat of little tremors ; then it 

 spreads itself around the crystal and dances excitedly. It may with- 

 draw for a short time and then make a fresh attack. The activity 

 ceases when the crystal is dissolved. Here one almost says it exer- 

 cises choice. The movements appear spontaneous. The resting state 

 that follows the battle seems to be a state of satisfaction. 



Doctor Loeb has performed a large number of experiments upon 

 starfish, medus^ie, worms, and insects, from which he concludes that 

 so-called instinctive acts are nothing more than mechanical effects of 

 such general forces as light, gravity, etc., acting in common upon 

 plants and animals. When the moth flies into the flame it is not 

 necessary to speak of its love of light ; or of danger when the mollusk 

 withdraws into its shell; or of discomfort when the crab is turned on 

 its back; or predilection for the dark when an animal avoids the light; 

 or of intelligent forethought when the fly lays its egg on objects 

 which serve the hatching larvae as food. The so-called purposeful 

 character of instincts does not distinguish them from reflexes. Nature 

 may say to her fishy children, "Bite at every worm, for there are 

 fewer impaled on hooks than not," and to the fly, "Try the web of 

 the wily spider." Instinct is usually defined as "the faculty of acting 

 in such a way as to produce certain ends without foresight of the 

 ends and without previous education in the performance." The con- 

 ventional discrimination between reflex and instinctive reaction does 

 not aid us in the understanding of these phenomena, for both are 

 concerned with reactions to external stimuli and conditions. The 

 latter is usually thought of as a chain of reflexes causing the whole 

 organism to react. It may be congenital. An organism replete with 

 motion behaves instinctively, and the nervous system serves as a 

 protoplasmic bridge or conductor from sense organs and muscles. 



The results of a few experiments by Loeb will better convey the 

 rmeaning of these statements. His conception of "tropisms" will ex- 

 plain the reactions in simple organisms and may be applied to some 

 'of the more complex reactions of higher animals ; at any rate, there 

 is a chance for such inference. 



The moth flying in the region of a strong light is drawn into it, 

 not through curiosity nor by attraction. The muscles on the side 

 toward the light are positively heliotropic, and the moth, a symmet- 

 rical thing, is turned in a medial line for the light, and, if flying 

 swiftly, has momentum to carry it into the flame. This kind of 

 orientation is familiar to the botanist. The udendrium in its stem 

 relations to the window illustrates the same principle. Simple chem- 

 al and mechanical effects on muscles turn the moth into the flame. 



