272 Life mill fatten* of Francis Gait on 



The more modern 8t4it istician would feel compelled to investigate to what 

 extent temper does change with growth, education and environment before 

 he could assert that it was as hereditary as any other (|Uiility. Putting 

 jiside these criticisms, (ialton undouhtedly indicated in tliis paper for the 

 fii-8t time that statistics of factore of character could be dealt with and 

 inferences drawn as to their distribution and hereditary character. 



In the previous year, 1886, (iaiton had pul)lishe(l at least two pai)ers 

 dealing with psychometry. Mr Joseph Jacobs had been interesting himself in 

 "Ex])eriinents on Prehension," which he defined as the mind's power o^takivg 

 on certain material, in this oise auditory sensations. Nonsense syllables, 

 letters or numerals were delivered at alx)ut half-second intervals in a 

 monotonous voice, and the test consisted in the numljer the subject could 

 repeat'. Mr Jacol)8 found that the 'span,' i.e. number correctly repeated, 

 (a) increased with age, (b) was greater for those higher in the class than 

 for tho.se lower, and argued that the 'span of prehension' should lie an im- 

 portant factor in mental groups, and its determination a test of mental 

 capacity. Galton suggested that the inquiry should be extended to idiots, and 

 visited on June 18, 188G, the Earlswood Asylum with Professor Alexander 

 Bain, and on June 30, 1886, the Asylum for Idiots at Darenth with Professor 

 James Sully. The general conclusion obtjiined by Galton was that the idiots' 

 'span of prehension' was only alxjut half that of Mr Jacobs' normal children, 

 three to four figures instead of seven to eight. 



In 1 886 Romanes published a theory of the origin of varieties, attributing 

 them to peculiarities in the reproductive system of certain individuals which 

 render them more or less sterile to other members of the common stock 

 while they remain fertile among themselves. Galton, who, as we have seen 

 (p. 271), had been working on assortative mating in man, considered that 

 special sexual attractiveness rather than sterility due to peculiarities of the 

 reproductive system was the source of varieties. He writes': 



"It has long seemed to me that the primary characteristic of a variety resides in the fact 

 that the indivichials who compose it do not, a.s a rule, care to mate with those who are outside 

 their pale, but form through their own sexual inclinations a caste by themselves. Consequently 

 that each incipient variety is probably rounded ofl' from the parent stock by means of pecu- 

 liari(if« of seirual instinct, which prompt what nnthropt)logists call endogamy (or marriage 

 witliin the triln; or caste), and which check exogamy (or marriage outside of it). If a variety 

 should arise in the way suppose«l by Mr liomanes, nierely because its members wore more or 

 less infertile with others sprung from the same stock, wc should find numerous cases in which 

 members of the variety consorte<l with outsiders. These unions might be sterile, but they 

 would occur all the same, supposing of course the period of mating to have remained un- 

 changed. Again we sliould find many hybrids in the wild state, l>elwcen varieties which were 

 capable of producing them when mated artificially. Hut we lianlly ever observe pairings 

 between animals of different varieties when living at large in the same or contiguous districts, 

 and wc Imrtlly ever meet with hybrids that testify to the existence of unobservo<l pairings. 

 Therefore it sctniis to me that the hypothesis of Mr Romanes would in these cases fail while 

 that which I have submitted would stand." (p. 395.) 



Gralton then suggests that even in the case of plants insects may exhibit 



' Mind, Vol. xil, pp. 75-9. 



» "The Origin of Varieties," Nature, Vol. xxxiv, pp. 395-6, August 26, 1886. 



