408 NATURE 
[Sep¢. 2, 1886 
On the other hand, if natural selection cannot thus operate, all 
we have to say is that there still remain many other causes ade- 
quate to explain the occurrence of physiological selection—to 
wit, those causes which are concerned in the occurrence of 
variation in general. 
The essay by Prof. Weismann on the influence of isolation, to 
which Mr. Meldola refers, is so replete with facts and arguments 
unconsciously bearing on my theory, that in writing my pre- 
liminary paper it appeared advisable to reserve so rich a mine 
for subsequent working out in detail. In my paper, therefore, I 
have merely alluded to Prof. Weismann as one among the com- 
paratively few evolutionists who have hitherto sufficiently con- 
sidered the influence of independent variation (or the prevention 
of intercrossing) in the evolution of species. 
It only remains to consider Mr. Meldola’s extremely able 
criticism of my view that natural selection ought not in strictness 
to be regarded as a theory of the origin of species, but rather as 
a theory of the development of adaptive modifications. My 
argument is that natural selection can only be a theory of the 
origin of species in so far as species differ from one another in 
points of utilitarian significance ; and that even then it is only a 
theory of the origin of species, as it were, incidentally: the 
raison d’étve of natural selection is in all cases that of evolving 
adaptations (whether these be characteristic of species only, or 
likewise of higher taxonomic divisions) ; and if in some cases 
the result of performing this function is that of raising a variety 
into a species, such a result is merely collateral, or, in a sense, 
accidental. 
one another in points of utilitarian character, the collateral 
nature of the result might be disregarded, and the theory would | 
become a theory of the origin of species in virtue of its being a 
theory of the development of adaptations. But, asa matter of 
fact, species are very far from being always and only distinguished 
from one anther in points of utilitarian character, and in so far 
in no sense a theory of the origin of species. 
to distinguish species from species is that of mutual sterility, and 
it would be a bold flight of speculation to affirm that this has 
been in all cases the result of natural selection, when even Mr. 
Darwin was reluctantly compelled to conclude that such could 
not be the result of natural selection in any case. On the other 
hand, my theory of physiological selection explains this very 
general feature of specific distinction quite independently of 
natural selection ; and then goes on to show that, when once 
this primary distinction has arisen, many others of a secondary 
kind will ensue, both with and without the assistance of natural 
selection. 
Now, the objection which Mr. Meldola adduces against this 
argument is that I t:ave not proved physiological selection to be 
independent of natural selection. In other words, he does not 
dispute the probable truth of my theory; but he says that, 
granting its truth, it is still only ‘‘ one particular phase of natural 
selection.” But surely the burden of proof here lies on the side 
of my critic. If he can show any sufficient reason for going 
much further than i have ventured to go in out-Darwining 
Darwin—or for holding that natural selection may not merely 
help in inducing sterility in some cases, but has been the sole 
cause of it in all cases—then I should welcome his proof as show- 
ing that the principles of physiological selection ultimately and 
in all cases rest on those of natural selection. But, clearly, it is 
for him to prove his positive : not for me to prove what I regard 
as an almost preposterous negative. 
So much for the main criticism. But he adds this rider, 
namely, that, as the struggle for existence is always most severe 
between the most closely related forms, unless the new or 
sexually protected form arising under physiological selection 
possesses some distinct advantage over the old or parent form, 
it will be exterminated by the latter quite as effectually as it 
would be by intercrossing in the absence of physiological selec- 
tion. To this I may answer in the words of my full paper :— 
“So long as there is no actual detriment arising to the variety 
on account of its being sexually separated from the parent, any 
ideas derived from the theory of natural selection are plainly 
without bearing upon the subject” (p. 406). In other words, so 
Jong as in all other respects of organisation the sexually sepa- 
rated variation is not less “fit” than its parent stock, so long 
there is no reason to anticipate any disadvantage in the struggle 
for existence. And forasmuch as the sexual separation arises 
only by way of a variation locally affecting the reproductive 
system, when the variation is first sexually separated, it will in 
No doubt if species always and only differed from | 
all other respects resemble its parent stock, and so be able to 
compete with it on equal terms—mere numerical inferiority 
being without significance where intercrossing is prevented. It 
was in order to convey this meaning that I proposed as an 
alternative name of my theory, ‘‘ Segregation of the Fit” ; seeing 
that before any physiological segregation can take place there 
must be organisms to be segregated, and that unless these 
organisms had already proved themselves fitted to survive in the 
struggle for existence, in existence they could not be. But I do 
not call physiological selection ‘‘ Segregation of the Fittest,” 
because, unlike natural selection, it is in no way concerned with 
the principle of conflict. So long as the organisms which have 
been separated by physiological selection ure sufficiently fit to 
have previously passed muster at the hands of natural selection, 
there is no reason why the daughter type should be fitter than 
the parent. 
But, so far as I can see, the only material point of difference 
between Mr. Meldola and myself consists in his regarding 
physiological selection as ‘‘subordinate” to natural selection, 
while I consider the two as quite independent principles, 
, although, as explained in my paper, I believe that they fre- 
quently and in several ways play into each other’s hands. 
GEORGE J. ROMANES 
Geanies, Ross-shire, N,B., August 30 
Earth-Currents and Aurora 
THERE appears to have been a very remarkable and wide- 
spread earth-current storm on March 30 last, full particulars of 
which it would be extremely useful to have on record. My 
attention has been drawn to this storm through witnessing, on 
the evening of that day, one of the most vivid and interesting 
a ae Seder ; | displays of the aurora that Ihave ever seen. Mr. G. H. Kinahan 
as they are not thus distinguished natural selection is obviously | Pay ane 
Again, and more | 
particularly, the one feature which more than any other serves | 
writing in Nature for April 8 (p. 537), describes the same 
aurora as observed by him in Donegal between 8 and g p.m., 
and notes its peculiar bright silvery type. It must, however, have 
| been a far less imposing display at Donegal, where the weather 
was less favourable, than at Kingstown, where I saw it between 
g and Io p.m., the most brilliant display occurring between 9.30 
and 9.45 p.m. From the northerly horizon there rolled up t> 
| the zenith in quick succession streams and masses of white light, 
until the whole face of the sky to the north and west was illu- 
minated with swiftly mounting flames of silvery whiteness and 
wonderful beauty. A correspondent in NATURE for April 15 
(p. 559) describes the same aurora witnessed by him between 8 
and If p.m. on March 30, at Konigsberg, in Prussia. 
According to the Zvectriciam (April 2, p. 404), on the morn- 
ing of March 30a violent earth-current storm occurred in London, 
stopping all telegraphic work for some time. During the same 
day strong earth-eurrents are reported on the Mediterranean 
cables, and in the afternoon of that day (March 30) this terrestrial 
electric storm had reached India, lasting from 2 to 5 p.m., and 
stopping work on the Bombay and Madras line. At the same 
time powerful earth-currents are reported on the Madras and 
Penang cable, causing work over it to be stopped from 3 till 
7 p.m. on March 30. Similar disturbances are reported on the 
Java cable, beginning the same afternoon, and becoming fainter 
on all lines at 10 p.m. Recently an account has been published 
of a great earth-current storm on the China and Japan cable on 
March 30, and a diagram of the perturbations produced on 
that line is given in the Zvectrictan for August 6. The storm 
began between 4 and § p.m., Shanghai time, on March 30, and 
lasted till 11 p.m. that day, the maximum strength of the earth- 
current on the cable occurring between 6 and 7 p.m. being 
then equal to 36 milliamperes. Smaller renewals of the 
storm took place both in Europe and Asia on the morning of 
March 31. 
Perhaps some of the readers of NATuRE can give further 
details of this extensive storm, and it would also be useful to 
have on record the magnetic perturbations noticed on this 
occasion in different localities, and the time of their occur- 
rence, W. F. BARRETT 
Royal College of Science, Dublin 
Chlamydomyxa in the Engadine 
Your readers will be interested to hear that I have found here 
in Pontresina the very interesting Protozoon described twelve 
years ago, in the Quarterly Fournal of Microscopical Science, by 
a 
wen ere 8 — 
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