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XXIV.—On the Pediculi infesting the Different Races of Man. By ANDREW 
Murray, Esq., of Conland. (With two Plates—X XIX. and XXX.) 
(Read 17th December 1860.) 
The bearing which the subject of the following communication has upon the 
much-vexed question of the unity of the human species, and the inferences which 
may be drawn from it in relation thereto, invest it with an importance which 
would not otherwise belong to it. 
The position which the question I allude to at present occupies is this. On 
the one hand, the advocates of the view that all men are not of the same species, 
but that they compose a genus consisting of many species, maintain that the 
parasites which infest the different races of man are distinct ; and because we 
usually find that ‘distinct species of parasites are allotted respectively to the 
different species of the lower animals, they infer that the same rule must hold 
with man, and that therefore each different race possessing a distinct parasite 
must be a distinct species. Their opponents, on the other hand, deny the fact 
that these parasites are distinct, asserting that one and the same species of 
Pediculus, and no other, infests all the races of man in every quarter of the globe; 
and I believe they add, that, even although they were found to be distinct, the 
inference thence drawn is neither necessary nor warranted. But, in the first | 
instance, the parties are at issue as to the question of fact. It may seem strange 
that this should be the case, as the very circumstance that the statement has 
been made and denied, implies that the subject or object has been examined by 
at least two observers (the first affirmer and the first denier), and probably by 
many more ; and unless the inquiry be attended with more than common diffi- 
culty, such an examination should have furnished materials for its settlement. 
The explanation of the discrepancy, and of the opposing opinions entertained on 
the subject, lies, 1 believe, in this, that the affirmative statement has probably 
been made on the strength of a comparison between the Pediculi found on the 
negro and those found on white men, the former being the exotic race most 
accessible to the observation of American ethnologists, from whom the above 
statement has chiefly emanated; and as the parasite of the negro is blackish, 
while that of the European race is whitish, the hasty observer has thereupon 
jumped to the conclusion that they are different ; while the more deliberate 
observer, who has noticed that the colour is greatly owing to the contents of the 
semi-transparent body, has, with similar inconsequence, come to the conclusion 
that there is no difference but that of colour; and that the colour of the parasite 
is solely owing to the hue of the pasture-ground. No other differences, so far 
as I know, have ever been noticed. 
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