May 18, 1899] 
NATURE 
SV 
in the present paper as “common warning colours, and 
the author proposes for them the term syzaposematic. 
Not the least satisfactory feature of the present sum- 
ming up of the position by Prof. Poulton is the distinct 
convergence of the evidence in favour of the natural 
selection theory which has been accumulated since 1879. 
The sacrifice of a certain percentage of individuals to 
the inexperience of their enemies was an assumption 
on Miiller’s part,and the present writer well remembers 
pointing out in a letter to that eminent naturalist that his 
case would be enormously strengthened if he would 
make observations on the spot. The result was a long 
series of a distasteful Acraea, collected by Miller in 
order to show that bird-pecked wings were of frequent 
occurrence. Much evidence of the same kind has been 
since obtained, and a most valuable series of experiments 
conducted by Mr. Finn, in India, during the years 1895- 
96-97, and published in the /owrnal of the Asiatic 
Society of Bengal, have led that author to the conclusion 
that unpalatable forms are by no means altogether free 
from attack. 
It must be further borne in mind that in 1879 the ques- 
tion of the non-transmission of acquired characters had 
not been brought into prominence. It was tacitly 
assumed in the theory of Bates that a knowledge of 
edible and inedible types could be transmitted by 
heredity. It is remarkable that Miiller, by virtue of his 
hypothesis, should have unconsciously challenged this 
tacit assumption by suggesting that young birds had to 
learn by experience, and did not derive their knowledge 
of eatable and distasteful forms by heredity. The whole 
tendency of Prof. Lloyd Morgan’s work of late years has 
been to confirm this suggestion by actual observation and 
experiment ; and Mr. Finn, also, in summing up his results, 
states that “each bird has to separately acquire its ex- 
perience, and well remembers what it has learned.” Thus 
the Millerian theory of 1879 has now been placed on a 
psychological basis of well-ascertained facts. 
Those who still believe that common warning colours 
can be explained by internal or external causes, as de- 
fined in the present paper, will, we imagine, find the 
ground crumbling away from beneath their feet if they 
will seriously weigh the arguments set forth by Prof. 
Poulton. What series of external causes in nature are 
there, for example, which can so act upon an organism as 
to modify only those-superficial characters which are re- 
quired to bring about a resemblance to another form 
while leaving all other characters unmodified? To 
attribute such modification to independent evolution by 
virtue of innate tendencies or laws of growth or internal 
forces, appears to the writer to be substituting mysticism 
for scientific explanation. What external agencies can 
be conceived which shall, while acting without visible 
result upon the early stages of all kinds of insects, 
culminate only in a resemblance between the imagos? 
The external conditions of life are imposing themselves 
during the whole of the larval and pupal existence, and 
yet these forms remain quite distinct, while the imagos 
come forth at once with all their disguising characters 
perfected. 
On considering again the undoubted fact that in many 
cases of mimicry and common warning colours the female 
only is affected, the inadequacy of any explanation de- 
pending on direct action of environment or internal 
evolutional “tendencies” becomes strikingly apparent. 
So also, as Prof. Poulton illustrates by a most remarkable 
set of examples, when insects of different orders resemble 
each other, the superficial similarity must necessarily be 
brought about by the most diverse kinds of modification 
of parts. To attribute such distinct and diverse modifi- 
cations of form, directed towards a common end, to 
similarity of external forces or internal tendencies, seems 
to the writer to be a straining of hypothesis beyond any 
degree of rashness attributed to the supporters of natural 
NO. 1542, VOL. 60] 
selection. What natural agency can be imagined that 
will account for the production of a similar colour in two 
or more species—in one form by developing pigment, and 
in another by developing striation of surface, so as to 
produce the same chromatic effect, excepting selection 
which works only for advantageous results irrespective 
of means? Even within the same order, where the 
resemblances might be more reasonably supposed to be 
due to similarity of external conditions, the likeness is 
superficial only, and is brought about by the most diverse 
means. There is apparently no chemical relationship 
between pigments which produce the same visual effect 
in mimetic butterflies of different families. A visual 
resemblance is required only by natural selection ; ex- 
ternal and internal causes have been incompetent in such 
cases to modify the more deeply concerned physiological 
processes so as to produce similarity of appearance by 
identity of pigment. Such a character as transparency 
of wing, also, is shown to have been attained by several 
distinct methods ; by reduction in the number of scales, 
by reduction in their size, by loss of pigment, by being 
set up on edge instead of lying flat, and so forth. Any 
common set of forces, external or internal, which can 
bring about the same result, viz. wing transparency, by 
such diverse methods is simply inconceivable. 
We have given only a few illustrations of the argu- 
ments which the author makes use of in this paper to 
dispose of the theories which have been advanced by 
way of substitutes for natural selection. As Prof. Poulton 
says In conclusion: “The review of the whole subject 
during the past thirty-six years increases our confidence 
in the theories of Bates and Fritz Miiller, while it dis- 
poses of all alternative hypotheses.” 
It should be added that many new examples of mimicry 
and common warning colours—some of them of the most 
striking character—are given in the paper. More par- 
ticularly will English entomologists be interested in the 
resemblance of the young larve of Stauropus fag? to an 
ant, and of the similarity in appearance and habit of the 
young larvee of Exdromis versicolor to saw-fly larve. 
R. MELDOLA. 
PROFESSOR CHARLES FRIEDEL. 
RANCE has lost one of her most distinguished 
chemists in the person of Prof. Charles Friedel, 
member of the Institute, who died at Montauban on 
April 20. He was born in Strassburg on March 12, 
1832. His father was a banker; his mother was the 
daughter of Dr. Duvernoy, well known in his day as a 
scientific man. He distinguished himself so greatly in 
his studies that he took his degree of Bachelor of Science 
with special honours. Desiring to follow science as his 
profession he went to Paris, and gained the special 
esteem of M. de Sénarmont, who caused him to be 
appointed conservator of the mineralogical collections 
at the Ecole des Mines. He worked in the laboratory 
of the distinguished chemist M. Adolph Wurtz, also a 
native of Alsace, at the Ecole de Médecine. In 1856 he 
married Miss Keechlin, by whom he had five children, 
one of whom, George Friedel, is known as a_professor 
at the mining school of St. Etienne. Mrs. Friedel died in 
1871, at Vernex, where she had retired during the Franco- 
German war ; and her husband, who was shut up in Paris, 
knew nothing of the sad event until after the city 
capitulated. He was married again, in 1873, to Mlle. 
Louise Combes, whose father was a member of the 
Institute of France, and who, with their son and a large 
circle of relations, now mourn his recent decease. To 
return to his professional distinctions : in 1869 he became 
Doctor of Science ; two years after he received a high 
appointment at the Ecole Normale Supérieure. In 1876 
he became Professor of Mineralogy at the Faculté des 
Sciences, at the Sorbonne ; and in 1878 he received the 
