4o8 



NATURE 



[January 24, 19 18 



overfeeding, however much it may affect weight, 

 has probably Uttle effect on adult stature, though 

 it may hasten growth and thus enable a man to 

 reach precociously his predestined stature." Of 

 great importance, however, are the internal secre- 

 tions of the gonads, the thyroid, the pituitary 

 body, and other endocrine glands. The degree 

 of activity exhibited by these glands is a variable 

 and heritable constitutional character, but it is 

 also modifiable by severe diseases and accidental 

 extrinsic influences. In two ways, therefore, 

 stature is affected by the degree of activity of the 

 ductless glands, and "experience points strongly 

 to the conclusion that internal constitutional 

 factors are more important than the ordinary en- 

 vironmental differences." 



The following are among the most important 

 conclusions which Dr. Davenport has reached. 

 One of the factors determining variation in 

 stature is variation in the age of the onset 

 of puberty. Parents deviating from the mean 

 in the same direction have on the average 

 less variable offspring than those of one short 

 and one tall parent. The offspring of two 

 tall parents are less variable in stature than 

 those of two short parents. When the stature 

 of both parents is very much above or below the 

 average, the children tend to repeat it, especially 

 in the direction of tallness. When the parents 

 are much below the average the offspring regress 

 towards mediocrity, but there is no (or little) filial 

 regression when the parents are much above the 

 average. It seems that parents of all statures are 

 somewhat heterozygous (or " impure ") as regards 

 their peculiarity, but there is evidence in favour of 

 the theory that in tall parents the gametes are 

 more nearly homogeneous (in lacking most of the 

 shortening factors) than are those of "short" 

 parents. Shortness seems to be due to certain 

 positive factors which inhibit the growth of vari- 

 ous parts. It appears that " growth-as-a-whole " 

 factors are present, hut there is a large degree of 

 independence in the variability of the four seg- 

 ments of stature (head and neck, torso, thigh, 

 and lower leg) ; and this makes impossible any 

 simple " Mendelian " laws of the inheritance of 

 stature as a whole. 



There is evidence that peculiarities in the sepa- 

 rate segments of stature are independently 

 heritable, and the combinations of types with dif- 

 ferent proportions (though similar in total 

 stature) may give curious, but readily intelligible, 

 results. The proportional shortness of any seg- 

 ment depends on more than one shortening factor 

 — just how many cannot be said. It is probable 

 that in all forms of dwarfing there are multiple 

 dominant inhibiting factors. In the case of 

 gigantism In both parents all the children are 

 tail ; ' ' this indicates that the factors for tallness 

 are mostly recessive — probably due to the absence 

 of Inhibitions, to prolonged growth." "Persons 

 of similar stature tend to marry each other; and 

 extremes are more particular In this respect than 

 those of medium statures." 



These are the most important conclusions of 

 NO. 2517, VOL. 100] 



this interesting piece of work, but it is evident 

 that ' ' the classic topic of the heredity of human 

 stature" must be subjected to further analysis 

 with even larger bodies of data. In admitting the 

 provisional character of his investigation, Dr. 

 Davenport says: "If the work has done nothing 

 more than prove, what might have been antici- 

 pated, that the apparent blending inheritance of 

 stature is due merely to the presence of multiple 

 factors, it may be justified." 



NOTES. 



In various parts of the country camouflaged houses 

 and hangars and vessels are to be seen by those who 

 have eyes to see, and it was stated officially on 

 January 14 that the Admiralty ^ad tested many 

 methods of disguising mercantile shipping. One of 

 these methods is to paint the ship with various quaint 

 combinations of different colours. But this does not 

 appear to have proved much of a success, though we 

 know in Nature of conspicuously patterned creatures, 

 such as the hoopoe, which are, in certain situations 

 and poses, endowed with what amounts to a garment 

 of invisibility. Another method, well iUustrated by a 

 model in. the British Museum (Natural History), de- 

 pends on what is sometimes called Thayer's law, thi 

 announcement of which was first made in Nature o' 

 April 24, 1902, by Prof. E. B. Poulton. A further 

 illustrated description of the principle was given in an 

 article in our issue of October 27, 1910. Mr. Abbott H. 

 Thayer, an American artist, was one of the 

 first to recognise that a high degree of invisibilitv is 

 conferred on certain birds by the simple adaptation 

 of being dark above and whitish below. He tool< two 

 wooden decoy ducks, and placed them against a sand- 

 bank. One was coloured like the sand, or coated with 

 sand ; the other was coloured on its upper parts darker 

 than the surrounding sand, and graded below to pure 

 white. At a short distance the first was still clearly 

 visible, but the second was quite lost against its back- 

 ground. The first bird was revealed by the dark shadow 

 below it ; the second was made invisible because the light 

 lower parts were neutralised by the shadow, while the 

 dark upper parts were toned down by the strong direct 

 light. The result is technically described as oblitera- 

 ti'on by counter-shadmg. Some modification of this 

 experii-nent has been tried on ships by differential 

 painting, but this device has not proved so successful 

 as had been hoped by those who knew how obliterative 

 it was in some birds and fishes. On some other quit( 

 different line, it is said, the Admiralty has discovered 

 a system of camouflage which will go far to baffle the 

 eves of submarines. 



It would appear from some recent statements by tht 

 Ministry of Munitions that the production of mineral 

 oil from native sources is engaging the close attention 

 of the Department of Mineral Oil Production. It may 

 be inferred that boring for petroleum in Great Britain 

 has not vet been attended with any success, and S( 

 far the opinions of the large body of British geologisi- 

 who were opposed to these boring operations appeal 

 to have been justified. Oil has, of course, contmued 

 to be produced in Scotland by the distillation of the 

 so-called oil shales of the Carboniferous Measures, and 

 it appears that the output of this oil is being pressed 

 to the utmost. It has been known for many years 

 that the Kimmeridge shales of Liassic age inthe south 

 of England are in places quite rich in oil, and a 

 succession of companies has attempted in the past to 

 create there a shale-oil industry on the same lines as 



