240 
LETTERS TO THE EDITOR. 
[The Editor does not hold himself responsible for 
opinions expressed by his correspondents. Neither 
can he undertake to return, or to correspond with 
the writers of, rejected manuscripts intended for 
this or any other part of Nature. _No notice ts 
taken of anonymous communications. ] 
Cré Magnon Man: Imprints of his Hand. 
WuiLe visiting lately the painted caves of the 
Cantabrian Mountains (north Spain) with Prof. Boule, 
who had kindly invited me to accompany him, I took 
advantage of this opportunity to study the imprints 
of the human hands which cccur on the walls of some 
of those caves, notably of Castillo. 
It is well known that at Gargas and elsewhere the 
imprints are those of a small hand, such as might 
have belonged to the Grimaldi race, and one such 
small imprint I observed in the cavern of Altamina. 
But in Castillo—so admirably described and _ illus- 
trated by the Abbé Breuil—I was surprised to find that 
all the impressions indicate an unusually large hand. 
With the permission of Dr. Obermaier, and the kind 
assistance of Mr. Burkitt, I was able to obtain trac- 
ings of seven of these, and two of them are complete 
enough for detailed study. One is 190 mm. in length, 
measured from the tip of the middle finger to the 
wrist, the other about 200 mm. This accords with the 
Fic. 3. 
length of the Cré6 Magnon hand as indicated by the 
description of the skeleton given by Dr. Verneau. 
This, however, is not all. When a tracing of one 
of the Castillo imprints is superposed on a tracing of 
the hand of a living subject (Englishman) having the 
same length, a characteristic difference is at once 
perceived. The fingers of the Castillo hand are 
shorter than those of the Englishman, and the equality 
in the total length is produced by the greater length 
of the palm. But this is a peculiarity which must 
have occurred in the Cré6 Magnon hand, for Dr. 
Verneau has shown that in the Mentone skeletons the 
metacarpals are disproportionately long when com- 
pared with the phalanges. 
I have made some preliminary measurements of 
tracings taken from the hands of twelve tall English- 
men, ranging from 5 ft. 83 in. to 6 ft. 03 in., with a 
mean of 5 ft. 11 in. (thus of about the Cré6 Magnon 
stature). Dividing the length of the middle finger by 
the length of the palm, I obtain 0-87 as the mean 
index, with a range of 0-77 to 1-0; while the most 
complete of the Castillo hands gives 0-765 and the 
next best 0-72 to 0-76. 
Thus the existence of two distinct races in the 
Aurignacian age, already indicated by the Mentone 
skeletons and the carved statuettes, receives additional 
confirmation. W.-J. Sonras: 
Oxford. 
NOn (2323, \,0lL.8 2) 
NATURE 
Ciba eee te a ee ee 
[May 7, 1914 
Cellular Structure of Emulsions. 
In reply to the letter of Prof. Kerr Grant in Nature 
of April 16, similar phenomena to those which he 
describes have been found to occur with minute motile 
organisms in water, and with sediments of various 
kinds in water and other liquids.. I have given an 
account of some of these appearances in my paper on 
the effect of gravity on the movements of micro- 
organisms in the Transactions of the Royal Society, 
series B, vol. cci., pp. 333-390. I have also obtained 
similar groupings with the fine sediment which is 
formed in a hypo-alum bath, used for toning and 
fixing P.O.P. prints. If a small quantity of this is 
poured into a shallow vessel, the particles which are 
at first evenly distributed through the liquid soon 
become aggregated into groups similar to those de- 
scribed by Prof. Grant. 
In the case of Euglena viridis, the living organisms 
in the dark become aggregated into groups as shown 
in Fig. 1, the central dark mass in each group con- 
sisting. of a stream of Euglene moving downwards, 
the lighter peripheral area consisting of Euglene 
moving upwards. Various sediments when allowed 
to settle in liquids become aggregated in a similar 
manner, but without the continuous up and down 
movements. Thus Fig. 2 shows a_ sediment of 
osmium dioxide settling in dilute glycerine, which 
closely resembles the aggregation of the living cells 
shown in Fig. 1 
In all the cases observed by me the regular group- 
ing appears to be preceded by the formation of a net- 
work, as shown in Fig. 3, formed by manganese 
dioxide settling in a solution of gum arabic. Again, 
if a readily oxidisable photographic developer is 
poured into a flat dish to form a layer about 1/16 in. 
deep, the brown oxidised film which forms at the 
surface is at once broken up into a network, Fig. 4, 
which gradually becomes resolved into separate 
groups. 
I have suggested that these groupings are in all 
_ probability cohesion figures, and that they may be 
related to the beautiful cohesion figures described by 
the late Mr. C. Tomlinson in the Philosophical Maga- 
zine for 1861 and 1864. They are probably formed 
whenever we have fine particles free to move, placed 
under such conditions that a force or forces, acting 
in opposition to the cohesion of the particles, can be 
brought into play. Cohesion, surface tension, diffu- 
sion currents, and gravity are among the forces prob- 
ably concerned in the effects observed. 
Prof. Grant’s suggestion that the flocculi in the 
solar photosphere and in cloud formations of floccu- 
lent type may be related to this phenomenon is in- 
teresting. Such flocculent appearances can also be 
observed, under certain conditions, in ponds and pools 
which contain dense aggregations of motile micro- 
organisms, and I have very little doubt that the net- 
