NoveEMBER 19, 1903] 
NATURE 
35) 
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Heating Effect of the Radium Emanation. 
A FORTNIGHT ago I wrote to you respecting the rise of 
temperature observed in radium compounds. I pointed out 
that the experiments of Profs. Rutherford and Barnes 
seemed to show that the effect was largely due to the 
excited activity. I have since then made a few experi- 
ments confirming that view. 
Air charged with radium emanation was led through a 
tube in which I placed a thermal junction formed by iron 
and nickel wires. The junction was left charged to a 
high negative potential during about ten minutes, then 
taken out and placed side by side with an unexposed junc- 
tion in a metal vessel kept at constant temperature by a 
water jacket. The two junctions at first seemed to be at 
the same temperature, but the exposed one began to become 
warmer almost immediately, and after twenty minutes was 
about one-tenth of a degree higher than the other junction. 
The experiment was repeated with the same result. Test 
experiments were made in various ways to show that acci- 
dental temperature disturbances could not affect the experi- 
ment. - Thus, after the wire had been treated exactly in 
the same way in a current charged with thorium eman- 
ation, the junction showed absolutely no change of tempera- 
ture detectable by the galvanometer used. 
We may draw an important conclusion from these experi- 
ments. Prof. Rutherford has given strong evidence to show 
that the excited activity really contains three successive 
stages of radio-active matter, the first changing into the 
second, and the second into the third; the fact that the 
_maximum heating effect was only obtained thirty minutes 
after the wire was first exposed to the emanation seems to 
show that it is the last transformation in which the third 
excited activity finally disappears or becomes inactive which 
sets the energy free. Experiments are now in progress to 
test the matter further. 
The _experiment mentioned above with the thorium 
emanation was not altogether satisfactory, and I should not 
at present like to draw the conclusion that the excited 
activity due to thorium does not give a heating effect. I 
only mention it here to show that the treatment of the 
wire in the experiment independently of the presence of 
radium does not give rise to such variations of tempera- 
ture as have been observed. Had any appreciable amount 
of the heating effect been due to the contact with the eman- 
ation, I should have expected the junction to show some 
rise in temperature when first introduced to the calorimeter. 
All these results should be considered as provisional only 
until a more detailed investigation has been made. 
ARTHUR SCHUSTER. 
The Owens College, Manchester, November 14. 
Radium and Animals. 
In the issue of Nature of November 5, Mr. Dixon gave a 
brief account of some interesting experiments with radium 
upon seedlings and upon Volvox, the results of which were 
almost entirely negative. Like Mr. Dixon, I have been in- 
vestigating the action of radium rays upon living matter, 
but in my experiments animals of simple structure have been 
employed instead of plants, and my experience leads me to 
think that the negative result of his experiments may have 
been due to the distance which separated the small quantity 
of radium he employed from the seedlings. 
In my experiments, which I have been carrying out in the 
university physiological laboratory, three lots of radium 
bromide were used, 5 mgr., 10 mgr., and 50 mgr. re- 
spectively. These were brought within 3 mm. of the cells 
containing the animals, the walls of which were made of 
thin mica instead of glass in order to lessen the absorption 
of the rays. 
NO. 1777, VOL. 69] 
It is too soon to discuss that obscure problem, the nature 
of the influence of the rays upon living matter, but it is 
already clear that experiments with simple forms of life 
will furnish some data. 
I have endeavoured to determine (a) whether the rays 
would provoke an immediate response of the nature of a 
contraction; (8) whether they would evoke the more 
generalised ‘‘ tactic ”’ response—that is to say, whether they 
would repel or attract the animals. Put very briefly the 
results are as follows :— 
(2) Actinospherium, with pseudopodia extended, exposed 
in daylight to 10 mgr. radium at 3 mm. did not retract its 
pseudopodia. In two hours, however, it was dead and 
breaking up. Controls were unchanged. 
Stentor—a green species. Two specimens were kept in 
the dark for some hours to increase their sensitiveness to 
radiant energy. On examination with a minimum of light 
the animals were found extended with cilia in rapid move- 
ment. Exposed to the rays from 50 mgr. of radium at 
4 mm. both slowly contracted, and slowly extended on re- 
moval of the radium. This observation was repeated 
three times. After the third exposure one Stentor refused 
to extend. 
(8) Stentor. Sixteen free-swimming specimens were 
placed in the dark in a cell over a lead plate 3 mm. thick 
with a hole in the centre about «mm. in diameter under 
which was 50 mgr. of radium bromide. Next day fifteen 
of the animals had attached themselves clear of the pencil 
of B rays, and one injured specimen was in the path of the 
rays. 
The cell was then moved so that a group of five came 
into the path of the 6 rays. In a few hours these were 
found to have detached themselves and moved out of the 
rays. 
Similar results were obtained on other occasions, though 
it seems possible for the rays to kill feeble specimens before 
they respond to the repelling influence. 
Hydra, both viridis and fusca, will, as a rule, detach 
themselves and move out of a pencil of B rays. If, however, 
the animal is again moved back into the rays from 50 mgr. 
at 4 mm. distance the third immersion is usually fatal—the 
tentacles drop off and the body slowly breaks up. 
Perhaps the most interesting result was obtained with 
Euglena viridis. Encysted specimens under the influence 
of radium rays (6 and y) in the dark readily become motile 
and disperse without suffering any harm. 
Newnhan College, Cambridge. E. G, WILLCOcK. 
Note on the Arctic Fox (Canis lagopus). 
A RATHER peculiar error in regard to this animal seems 
in danger of being perpetuated in certain contemporary 
literature, in which it is stated that, while in the other 
regions of its distribution the Arctic fox generally acquires 
a white winter coat, in Iceland this change never takes 
place, but that all the foxes there are blue. As a matter 
of fact, this fox turns white in the Icelandic winter as else- 
where, with this reservation only, that the proportion of 
blue winter forms there is greater than the proportion in 
the Arctic regions generally, the white forms, however, 
probably still remaining in an actual majority. I believe 
this occurrence of the white phase in Iceland is so far well 
known that I need not dwell on the evidence for it; from 
personal experience, however, I can corroborate it. It is a 
small point, but in so far as error is abroad, it seems 
advisable to correct it. 
In Iceland I was informed that the white form and the 
blue were distinct, and in his work on this island a century 
and a half ago, Horrebow was of the same opinion. This 
view is based on the fact that both Horrebow and the 
Icelanders had seen white foxes in full summer, and is no 
doubt to be explained by the fact that occasionally the white 
dress is not changed for the summer brown. On the other 
hand, I believe that some authors still maintain the distinct- 
ness of the two forms, though I am not aware how they, 
overcome the evidence of those who have observed the 
phases intermediate between the two which occur at the 
moulting season. 
In his ‘“‘ Colours of Animals ’’ Prof. Poulton quotes the 
