October 7, 1920] 



NATURE 



'83 



Such feathers show a faint yellow colour by 

 transmitted light, and any pressure which destroys 

 the structure also destroys all colour. The small 

 bodies which scatter the light are in this case 

 said to be exceedingly minute air-canals, which, 

 on being filled with fluid, lose this property. In 

 the case of feathers, as well as of certain animals, 

 such as green frogs and many reptiles, the green 

 is said to be due to the additional effect of a yellow 

 pigment which is superimposed on the blue colour, 

 as in the case of Ornithoptera poseidon, already 

 described. There are also some exceedingly 

 brilliant marine copepods which owe their colours 

 to a prismatic layer of minute rods, said to be 

 small enough to scatter coloured light. 



In most beetles the metallic colours are seen to 

 come from the surface, and the slightest scratch 

 on the elytron removes all the colour. In the 

 case, however, of certain emerald-green and blue 

 Cetoniids, the colour appears to come from under- 

 neath the surface, which gives the wing-case a 

 curious enamelled appearance. This p>eculiarity 

 can be instantly recognised, and, moreover, the 

 colour, though matt, is seen to persist, even when 

 the surface layer has been removed with a scalpel. 

 This layer has been called the " Emails chicht," and 

 when sections are cut from it tangentially to the 

 surface, 6 (Fig. 2), they give a bright green 



colour by reflected light, even when mounted trt 

 fluid media. A transverse section, 7 (Fig. 2), was 

 cut from this layer of a beetle called Hetcrorrhina 

 elegans ; it is seen to be made up of very fine rods 

 of chitin, r,, about ijx apart, and arranged at right 

 angles to the surface ; r^ represents a second layer 

 of rods at a lower depth. The section, 6 (Fig. 2), 

 made through the line ah of section 7, reveals the 

 cut ends of the rods. Thus the light, on striking- 

 the wing-case, is reflected from the tips or ends of 

 a large number of these rods or pillars, and it 

 seems possible that they may scatter the light in 

 the same way as the air-canals do in the case of 

 birds' feathers. It must, however, be pointed 

 out that the above theory demands that the rods, 

 or other bodies which scatter the light, should be 

 appreciably smaller than the wave-length of light ; 

 that is to say, not much larger than a complex 

 molecule. It is, however, uncertain whether 

 bodies of the same order of magnitude' as light 

 waves {i.e. o-^-i-Ofi) can produce analogous 

 colours. A very remarkable point about these 

 rods of chitin is that under crossed Nicols they 

 appear to be doubly refractive. This suggests 

 that there may be some analogy with doubly re- 

 fractive striated crystals like the tourmaline. 



(To he continued.) 



Physical Anthropology of Ancient and Modern Greeks. 

 Bv L. H. Dudley Buxton. 



T N classical times a clear distinction was drawn 

 ■*■ between Greek and Barbarian ; Aristotle, 

 indeed, claimed that they differed physically. To 

 a certain extent it may be shown that in detail 

 Aristotle had right on his side, bdt it can also be 

 shown that Greek differs physically from Greek, 

 so that his general thesis is untenable. It is true 

 that most of our evidence rests on measurements 

 made on modern Greeks, but there are data to 

 prove that the latter possess physical character- 

 istics not differing essentially from those of the 

 former. 



Among recent writers it has been generally ad- 

 mitted that at least two races are represented in 

 Greek lands — the "Mediterranean" and the 

 "Alpine." The former are .short in stature, dark 

 in colouring, and long-headed, typically repre- 

 sented by the Spaniards ; the latter are fairer, and 

 often, but not invariably, have auburn hair and 

 hazel eyes, and vary very much in stature. The 

 Eastern branch of the Alpines are usually known 

 as "Armenoids." They are distinguished by their 

 short, high heads, which are extremely flattened 

 in the occipital region. It has also been suggested 

 that long-headed, blond giants — Nordic — have con- 

 tributed to the population of Greek lands. 



Of the aboriginal population there is little 

 evidence at present. Von Luschan believes that, 

 at any rate in Anatolia, the earliest people were 

 Armenoids, and in the Morea Prof. Myres con- 

 siders that the Alpine strain is certainly ancient 

 NO. 2658, VOL. 106] 



and may even be primitive. Early material is, 

 however, so rare that it is easier, in stating the 

 problem before us, to reverse the time process and 

 to study the ancient people after the modern, 

 about whom we are better informed. 



The mean cephalic index in Greek lands to-day 

 varies from 79 in Crete to 84 in the island of 

 Leukas. None of the Greeks are as long-headed 

 as the pure Mediterranean type, such as we find in 

 a comparatively pure form in Corsica or Spain 

 and in a less pure form in Egypt ; nor, again, are 

 they as broad-headed as the Lycian gipsies, who 

 certainly represent pure Armenoids. If we group 

 such cephalic indices on the living as are available, 

 we obtain three classes: (i) Under 81, Cretans, 

 Peloponncsians, Lycians (Greeks and Turks) ; (2) 

 intermediate, Messenians and Cypriots ; (3) more 

 than 84, Leukadians, Albanians, Lycian gipsies. 

 It would appear unlikely that this grouping is of 

 any significance, if we turn from these figures to 

 the variation, conveniently measured by taking the 

 square root of the average square deviation from 

 the mean (standard deviation). The Lycian Greeks 

 and Turks have a very high standard deviation, 

 suggesting considerable mixture, and the standard 

 deviation of the cephalic indices of all the Greeks 

 is sufficient to suggest a greater or less degree of 

 intermixture. The condition of intermixture in 

 Cyprus can be seen in Fig. i — a photograph of a 

 Cypriot woman and her three children. The elder 

 boy might easily have been taken for an almost 



