a May 12, 1923 | 
aa 
i 

NATURE 
637 

Breeding Experiments on the Inheritance of Acquired Characters.* 
By Dr. Paut KAMMERER, University of Vienna. 
: 2 eon a quarter of a century has passed since 
I commenced to examine the inheritance of 
certain breeding- and colour-adaptations which I had 
obtained with amphibia and reptiles. I did not 
expect, in relatively so short a time, to obtain positive 
results, and, moreover, I was then well under the spell 
of Weismannism and Mendelism, which both agree that 
somatic characters are not inherited. 
In the year 1909 I succeeded in ascertaining that 
Salamandra atra and Salamandra maculosa can be so 
bred as to produce a complete and hereditary inter- 
change (of reproductive characters). The fact that 
Salamandra atra, which propagates itself in a highly 
differentiated manner, can be made to propagate itself 
in the manner of Salamandra maculosa need not 
necessarily be regarded as the acquisition of a new 
character, but may be an atavism. Since, however, 
the breeding habits of Salamandra maculosa can be 
changed to those of Salamandra atra, this objection 
is (in this case) excluded. I have hitherto always 
believed that no true inheritance underlay this pheno- 
menon, but only the appearance of heredity (Schein- 
vererbung)—the external conditions applied (such as 
moisture) affect the germ plasm in the direct physical 
and not primarily physiological manner. 
In view of my researches on the change of colour in 
Salamandra maculosa 1 could no longer entertain this 
belief. If the young animals are kept on a black back- 
ground they lose much of their yellow marking and, after 
some years, appear mainly black. The offspring of 
these, if kept again in black surroundings, bear a row 
of small spots, chiefly in the middle line of the back. 
If the offspring, however, unlike their parents, are 
aah on a yellow background, these spots fuse to a 
nd. : 
The yellow markings of the parent generation reared 
in yellow surroundings increase at the expense of the 
black colour of the Salamandra. If now the descendants 
of such strongly yellow individuals be kept on a yellow 
background, the yellow portions grow and appear as 
wide bilateral stripes. Descendants, however, which, 
unlike their parents, are now kept on a black back- 
ground have less yellow, but proportionately far more 
than the background produces in the offspring of 
parents raised in black surroundings. The yellow 
markings are arranged symmetrically in rows of spots 
on both sides of the body. 
It could now be said that the diminution of that 
colour which in the parents has become increased 
exhibited the nature of a non-inheritance. The ac- 
quired colour does not remain constant but diminishes. 
Ultimately, the grandchildren would have regained the 
same colour distribution as that of the initial parents. 
Therefore it could be argued we have merely an after- 
effect and not inheritance. 
Against this view, however, we have to consider 
several points. (1) Young Salamandra kept on a 
black background, and reared from parents which had 
not been kept in yellow surroundings, become blacker 
in a much shorter time than those (on a black back- 
: —— delivered before the Cambridge Natural History Society on 
April 30. 
NO. 2793, VOL. I11] 
ground) which had been reared from parents kept 
in yellow surroundings. (2) The descendants in my 
experiments are not merely placed in intermediate con- 
ditions (for example, a mixture of yellow and black 
backgrounds), as was done in most other breeding 
experiments on the inheritance of acquired characters— 
for example, those of Standfuss and Fischer on butter- 
flies and of Sumner on mice. But the descendants are 
placed in opposite conditions: strongly yellow Sala- 
mandra are placed on a black background, and vice 
versa. Each tendency must be neutralised by the 
opposing stimulus ; it cannot be thought that living 
matter behaves in this respect differently from non- 
living matter. (3) The yellow colour of the Sala- 
mandra, which descends from parents which have 
_become very yellow, has at first a tendency to increase 
in spite of the opposing effect of black surroundings. 
The rows of spots of the freshly metamorphosed animals 
tend to fuse into stripes, just as in the case of animals 
brought up on a yellow background. Only later these 
stripes break up into spots again. 
Curt Herbst, in 1919, reproached me by saying that I 
did not mention the augmentation of yellow pigment 
on a black background, and vice versa. It can be seen 
from my slides, which I have already shown in 1909 to 
the Congress of German Naturalists in Salzburg, and 
in rg1o to the International Zoological Congress in 
Graz, that I have made this augmentation clear. I 
have always emphasised this phenomenon of inherit- 
ance, which Herbst did not recognise as such. 
Finally, we must not neglect how I have selected my 
material. For the experiments on a black background 
I used Salamandra which were richly marked with 
yellow ; for those on a yellow background, Salamandra 
which were least marked with yellow. I used, there- 
fore, a negative—or contra—selection to exclude the 
objection that I was using animals specially suitable 
for the colour changes which they had to undergo. I 
had, indeed, to contend with the fact that my animals 
were specially unsuitable for the experiments. Those 
which would have to change their colour to black were 
apparently burdened with a tendency to yellow, 
while the others which would have to produce a yellow 
race would have to contend against an opposing in- 
heritance influence. 
In the Vienna woods, where I had myself collected 
my experimental material, there were only asymmetric- 
ally spotted Salamandra (forma typica). My breeding 
experiments had changed the spotted Salamandra into 
the striped form. The striped race (forma taeniata) 
occurs also in the open; it is true, not in Vienna, but 
in districts where the earth is coloured yellow or 
yellowish red. In the experiments which I am about to 
describe I used Salamandra from the Harz Mountains, 
and it was found that the young of these (as in the 
experiment) immediately after metamorphosis already 
possessed their ¢aeniata markings. In another case, 
that of Salamandra originating from the surroundings 
of Heidelberg, the freshly metamorphosed young were 
irregularly spotted, as in forma typica, and only arranged 
their markings during their growth into faeniata. Curt 
Herbst has noticed this ontogenetic recapitulation, 
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