568 MR ANDREW MURRAY ON THE PEDICULI 
Feeling it to be desirable that the matter of fact should be ascertained,—that, 
whatever may be the result, and whatever effect that result may have on the 
question into which its services have been pressed, we should at least know what 
the truth really is,—I have taken advantage of the opportunities which a some- 
what extended correspondence with foreign countries has put in my hands, to 
endeavour to find out how the fact stands; and I propose now to submit to the 
Society the result of my inquiry. 
I would premise, however, that the inquiry has not been made without 
difficulty, and on that ground solicit indulgence for the imperfections and blanks 
which I have been unable to supply. The chief difficulty was to procure speci- 
mens, which could only be done by inducing friends to interest themselves in the 
matter. 
But the difficulty of procuring specimens is not all. There are other elements 
involving doubt which must be kept in view: one is their size, and the other their 
colour; what attention, if any, is to be bestowed upon either? As the Pediculus 
does not, like most other insects, pass through metamorphoses after issuing from 
the egg, but merely changes its skin, individuals are to be found of all sizes; 
and, unlike the beetle or the butterfly (which, after emerging from the chrysalis, 
never increase in size), individuals grow larger, merely changing their skins a 
certain number of times. All comparison of actual size is thus excluded up to 
a certain age. After their last moult, however, the skin assumes a stronger con- 
sistency and more decided colour, and a full-grown specimen can usually be 
recognised as such. In my examinations I have uniformly rejected half-grown 
individuals, and only compared those which, from their size, texture, and colour, 
appeared to be adult. 
The value of colour as a character is a point of greater difficulty. As I have 
already remarked, it is colour which has given rise to the statement that different 
species are peculiar to different races. There is no doubt that the species found 
on the white man are pale, and those on the black man dark. But in most other 
cases among insects, colour per se is either ignored as a character altogether, or 
admitted with the greatest diffidence. Further, colour may be derived from 
the nature of the feeding-ground; and it is stated by some, that if a white 
specimen, taken from a white man, be put upon a black man, it will become black, 
and vice versa. The Rev. Mr Histop, known as well for his scientific as for his 
missionary labours in India, informs me that at Nagpore he thinks he has seen 
dark Pediculi, which have found their way from coloured nurses to white children, 
after a time becoming white; and another friend has informed me that on one 
occasion, when seated in church behind two lads—the one dark-haired and the 
other light-haired, both swarming with vermin—he noticed that those upon the 
dark-haired lad were darker than those on the light-haired one. Such circum- 
stances would seem to indicate that colour was accidental, and therefore of no 

