502 



KNOWLEDGE. 



December, 1910. 



at low potential. The point at low potential deter- 

 mines the direction in which the spark \\ill lea\e the 

 point at high potential. The passage of the spark 

 through the air reduces the resistance of its track, 

 though this reduction lasts for a comparati\el\' short 

 time compared with the diminution produced in the 

 neural track connecting a and b in the cortex of 

 the brain. 



The condition, however, to which I wish to direct 

 special attention is that the difference of potential 

 required to form an association track between o and 

 h is only produced when the wave of e.xcitement 

 passes through a immediateh' before the second wave 

 of excitement passes through h. It is necessar\- also 

 that the excitement of a shall lie \cr\- much reduced 

 before b is excited. 



The conclusion forced ujion us b\' the abox'c 

 considerations is that anj-thing which retards the rate 

 at which the excitement of a neural system dies out, 

 reduces its power of forming associations with other 

 neural systems. T>ut when once an association, i.e.. 

 a track of low conductivitv is formed, sav, b\- 

 sufficient repetitions, the nervous currents whicli 

 i\o\v through the track will last longer. 



Now, the property of high persistence, orPerse\er- 

 ation, which we measure by the apparatus described 

 above, will have the effect of retarding the disappear- 

 ance of the excitement in a neural s\stem. 



We should expect, therefore, that persons with 

 high Perseveration would form new associations with 

 great difficulty, and persons with low Perse\eration 

 would form them with great ease and rapiditx'. 



Dr. Otto Gross, in his treatise on the Secondarv 

 F"unction, has deduced in a most ingenious wa\-. 

 from this physiological hypothesis, the different kinds 

 of mental character that are likely to arise, from 

 various amounts of the secondary function, or, as we 

 have called it. Perseveration. 



From the conclusions arrived at by Gross I ha\e 

 drawn up a scale of Perseveration, and the kind of 

 character likel}- to be associated w ith different degrees 

 of Perseveration, in the ordinar\' conditions of life. 



At the centre of the scale we ha\'e the average 

 amount of Perseveration, whicli is associated with 

 the practical common sense of the average man. 



When the Perseveration is below the average the 

 speed with which ideas flow through the mind is 

 quickened, and the readiness witii which the mind 

 receives external impressions is also increased. 



The first categor\- below the average, therefore, 

 contains persons with wittw brilliaiit. and suggestive 

 minds, persons of great tact, presence of minil, and 

 daring ; all of which im[>h- (]uick response to external 

 stimuli. 



To this class would tielong the majority of persons 

 who are popularh- considered to be geniuses. But 

 if we adopt Carlyle's definition of genius as "an 

 infinite capacity for taking pains," the genius would 

 have to be looked for in the class having Persevera- 

 tion one degree above the average. 



The category with Perseveration one degree above 

 the average contains persons who are fond of 



abstract thinking, and who follow a theme into all 

 its ramifications. The\' think slowh' and learn 

 slowK. The scope ot their consciousness is wide, 

 l)ut thc\- are not quick of apprehension because they 

 do not respond readil\- to outside stimuli. 



\\'e ma\' sa^•, therefore, that the classes with Per- 

 severation one degree below the average and w ith one 

 degree above the average, produce geniuses of different 

 types, who. while the\- excel in one direction, have also 

 certain defects associated w ith their excellent qualities. 



When we pass to the classes of persons \\ith 

 Perseveration two degrees above or below the 

 average, these defects are intensified, and serious 

 deterioration of mental character begins to appear. 



The category \\'ith Perseveration two degrees below 

 the average contains persons who cannot keep their 

 thoughts long on one theme : frivolous persons who 

 are fond of superficial associations, such as punsters 

 and c\'nics: [lersons to whom all emotions are of 

 equal \alue and who are consequently of weak moral 

 character; persons who learn an\'thing new very 

 ipiickly but superficially. 



On the other hand, the categor\' with Perseveration 

 two degrees above the ax'crage contains persons with 

 quite opposite defects. The long duration of the 

 secondar\- function interferes with the formation of 

 wide associations, and renders the limited associa- 

 tions formed exceedingly stable and inaccessible to 

 outside influences. This corresponds to the person 

 with fixed ideas, apparently founded on sentiment 

 rather than on reason. Gross somewhat invidiously 

 includes m this category vegetarians and anti- 

 vaccinators, but it is preferable to lea\e the truth of 

 that assertion to be determined by experiment. 



When Perseveration falls below, or rises abo\e that 

 of the two categories last described, the mind becomes 

 unstable — we pass from the sane to the insane. 



The insanit\' at the two extreme ends of the scale 

 is of quite different types. Persons with excessively 

 low Perse\eration are liable to acute mania, and 

 persons \\ith excessiveh' high Perseveration usually 

 suffer from inclancholia. 



The s\'iu[itoms of these two classes of the insane 

 are deducible bv Gross's hypothesis from the influence 

 of excessiveh- low or excessiveh' high Perseveration 

 on the formation and action of the mind. 



A considerable number of persons of both sexes 

 ha\e been measured with tlie revohing mirror 

 apparatus, in the Anthropometric liureau at the 

 Japan -British Exhibition. 



Though tile whole of the data obtained has'e not 

 \'et been anah'sed, the following are some of the 

 results (}litained from the measurement of eighty- 

 two men and twent\'-six women. 



CoMI'AKISON OF THE PERSEVERATION 



OF THE Two Sexes. 



The first question I set out to determine was 

 whether there was any significant difference between 

 the average Perseveration of the two sexes. 



I found that the mean Perseveration of the 

 eiuht\-two men was 15J"6 units: while the mean of 



