Literary Notices. 205 



rules which certain classes of reflexes follow. These descriptions are given in 

 terms of the reflex figure, a most convenient scheme for the presentation of the total 

 visible effect of a given stimulus or stimulus complex. "Thus at any single phase 

 of the creature's reaction, a simultaneous combination of reflexes is in existence. 

 In this combination the positive element, namely, the final common paths (motor 

 neurone groups) in active discharge, exhibits a harmonious discharge directed by the 

 dominant reflex-arc, and reinforced by a number of arcs in alliance with jt. * * * 

 But there is also a negative element in this simultaneous combination of reflexes. 

 The reflex not only takes possession of certain final common paths and discharges 

 nervous impulses down them, but it takes possession of the final common path 

 whose muscles would oppose those into which it is discharging impulses, and 

 checks their nervous discharge responsive to other reflexes. * * * In this way the 

 motor paths at any moment accord in a united pattern for harmonious synergy, 

 cooperating for one effect" (p. 178). A number of reflex figures, with their respec- 

 tive nervous patterns, are described in detail. 



A good illustration of the author's aptitude for indicating the utility and 

 developmental conditions of activities is furnished by the following fragment from 

 the discussion of immediate induction. "If a parasite in its travel produces excita- 

 tion which is but close below the threshold, its progress is likely to so develop the 

 excitability of the surface whither it passes that the scalptor-reflex \\ill be evoked. 

 In the skin and the parasite respectively we have, no doubt, two competing adapta- 

 tions at work. It is perhaps to avoid the consequences of the spatial spread of the 

 "bahnung" that the hop of the flea has been developed" (p. 184). 



In the competition of reflexes for the use of a common path dominance is deter- 

 mined in large measure by four factors: spinal induction, relative intensity of the 

 stimulus, relative fatigue, and the functional species of the reflex. Each of these 

 factors has been investigated by the author and receives adequate consideration in 

 the lecture on the successive combination of reflexes. Concerning fatigability and 

 its excuse for existing, he writes in his characteristic style: "The waningof a reflex 

 under long maintained excitation is one of the many phenomena that pass in 

 physiology under the name of 'fatigue.' It may be that in this case the so-called 

 fatigue is really nothing but a negative induction. Its place of incidence may lie at 

 the synapse. It seems a process elaborated and preserved in the selective evolu- 

 tion of the neural machinery. One obvious use attaching to it is the prevention 

 of the too prolonged continuous use of "a common path" by any one receptor. It 

 precludes one receptor from occupying for long periods an effector organ to the 

 exclusion of all other receptors. It prevents long continuous possession of a com- 

 mon path by any one reflex of considerable intensity. It favors the receptors tak- 

 ing turn about. It helps to insure serial variety of reaction. The organism, to be 

 successful in a million-sided environment, must in its reactions be many-sided. 

 Were it not for such so-called "fatigue," an organism might, in regard to its recep- 

 tivity, develop an eye, or an ear, or a mouth, or a hand or leg, but it would hardly 

 develop the marvelous congeries of all those various sense organs which it is actually 

 found to possess" (p. 222). 



Under the subject, species of reflex, it is convincingly argued, in the light of a 

 wealth of experimental evidence, that reflexes initiated by noci-receptors (such as 

 are especially adapted to the reception of nocuous or harmful stimuli) are pre- 

 potent. Such stimuli do not demand specialized sense organs adapted to a particu- 



