Letters to the Editor. 
[The Editor does not hold himself responsible for 
opinions expressed by his correspondents. Neither 
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Dr. Kammerer’s Alytes. 
TuHosE who have followed the discussion of Dr. 
Kammerer’s claims will be aware that special interest 
has centred on the question whether he could pro- 
duce for examination males of Alytes showing the 
modification alleged to occur in consequence of his 
treatment. Some of the circumstances which aroused 
scepticism are related in my letter to NATURE, July 3, 
1919, p. 344. We were originally told (Arch. Entwm., 
1909) that nuptial callosities or Brunfischwielen ap- 
peared on the thumbs of males of the treated strain, 
and that in the 5th treated generation (Kammerer’s 
F,) all the males had these structures. They are a 
conspicuous feature in most Batrachia, and Alytes is 
one of the few forms in which they are not known to 
occur. Since normal Alytes mate on land and the 
treated animals were made to pair in the water, we 
were asked (1909, pp. 516-7) to see in these Schwielen 
a true functional adaptation. The rugosities were 
developed to give the males a better grip of the 
slimy females. 
Dr. Kammerer remarks that any one who has 
compared the feel of a dry toad with that of a wet 
one will not question that rugosities on those parts 
of the limb which come into contact with the body 
of the female are a very necessary equipment for an 
aquatic embrace (p. 516). This theme was developed 
at considerable length. In Arch. Entwm., 1919, the 
same argument reappears, and, various other hypo- 
theses being discussed and set aside, it is argued that 
the most probable cause of the development of 
Tugosities was to be found in the change of mating 
habits. The process of mating in the water takes 
twice or thrice as long and is far more laborious. If 
his interpretation is right, Dr. Kammerer continues, 
the development is to be regarded as a “ funktionelle 
Anpassung: ihre nachweisliche Erblichkeit wiirde 
hierdurch an theoretischer Tragweite gewinnen”’ 
(Pp. 339). 
tis to 1919 nothing but vague diagrams (1909, 
Figs. 26 and 26a) had been offered us to show what 
these new organs looked like, and no detailed descrip- 
tion had appeared. Dr. Kammerer in that year | 
published the long paper mentioned above, making 
some new statements which I will consider presently. 
In illustration a photograph of the whole animal 
(F,; in 1913) was given. This picture was rather like 
those handed about a few years ago as “ spirit- 
photographs,”’ and for demonstrational purposes was 
worthless. There were also several drawings, and a 
photograph, representing sections through the skin 
of a supposed Schwiele. At about that time Dr. 
Przibram was good enough to send me a slide with 
six similar sections labelled 
shown to numerous colleagues. As regards the sec- 
tions and representations of sections, I do not ques- 
tion that they may have been taken through real | 
incipient rugosities, but the development is slight 
and ambiguous. 
The description of r919 amplifies that of ten years | 
before. The rugosities were originally described as 
in the proper place, namely, on the upper (sc. dorsal) 
and radial surface of the thumb; and as more males | with the female. 
NO. 2796, von. 111 | 
‘Ej;  owhiche eeaave | 
NATURE 

[JUNE 2, 1923 
of F, and F, came into breeding condition, rugosities 
appeared not simply on the bases of the thumbs but 
extended in various degrees and with individual 
differences up the inside of the forearm. Inasmuch 
as various Batrachians have rugosities in that region 
(showing also individual differences and asymmetries), 
and since in the embrace of Alytes the parts named 
are in contact with the female, the new account 
raised no fresh improbability—rather the contrary. 
Many modified males are said to have been under 
Dr. Kammerer’s observation during three years after 
he had (1910) been challenged to produce one, but 
a photograph of a single specimen—and that abso- 
lutely non-committal—was all that had been pub- 
lished to show the structures in position. We are 
told that the 1913-hatched brood failed to breed, and 
the last male (F,) died in 1914 (1919, p. 328). 
But one specimen (presumably that photographed) 
was known to be preserved in Vienna. It had been 
examined by visitors to the Versuchsanstalt, who 
reported verbally and variously as to what they had 
seen. A few weeks ago the announcement was made 
that this Alytes would be shown in Cambridge, and 
I received an invitation to attend a meeting at which 
it would be exhibited. Knowing that Dr. Kammerer 
had abstained from appearing at the Congress of 
geneticists which met at Vienna in September last, 
I inferred that he had no new evidence to produce, 
and I therefore excused myself from attendance, not 
wishing to enter deliberately into what was likely to 
prove a profitless altercation. When, however, an 
exhibition before the Linnean Society was arranged, 
I naturally attended as a fellow of the Society to 
see what I could. I expected to see a dark mark on 
the thumb or other fingers extending perhaps more 
or less over the wrist or up the forearm ; and whether 
this was to be interpreted as a nuptial rugosity or 
not, would, I imagined, be more or less a matter of 
opinion. 
What I did see was something altogether different. 
The animal was fastened with its back against an 
opaque plate in a cylindrical museum glass, with the 
ventral surface exposed. The right hand showed 
nothing special, but acvoss the palm of the left hand 
was a broad dark mark. It looked like a piece of 
thickened, blackish-brown skin. Examining it with a 
good lens I could see no papillary or thorny structure, 
though considering the minuteness of the alleged 
spines, I scarcely expected to make them out very 
distinctly. But the appearance was quite unlike that 
of any natural Brunftschwielen. In them, even in 
Rana agilis which has them developed very slightly, 
one sees with a lens characteristic grey specks, not a 
dark uniform surface as in the creature exhibited. 
I do not mean that there was no break in the pad as 
a whole, about which my memory is doubtful, but 
that the surface was uniform and the colour con- 
tinuous in tone, without the dotting or stippling so 
obvious in true Brunftschwielen. That there was no 
development on the right hand was explained. The 
skin had been snipped off during life to furnish 
sections. 
A photograph of the palm of a hand was thrown 
on the screen. This palm was pointed to as showing 
rugosities, but I saw none. In the specimen ex- 
hibited, the backs of the digits were not visible, nor 
were we shown any photograph of them. 
I direct attention first to the fact that the structure 
shown did not look like a real Brunftschwiele. Next 
I lay stress on its extraordinary position It was in 
the wrong place. Commenting on the evidence, I — 
pointed this out. In the embrace of Batrachians the 
palms of the hands of the male are not in contact — 
Those who looked at the specimen 
a ee eee 

