Hæmoglobin in the ‘Chromotrope’ of an Insect Parasitic Nematode

Abstract

IT is many years since Cobb examined, with a ‘spectroscopic eyepiece’ fitted to his microscope, the patch of red pigment found at the anterior end of the egg-laying female of the insect parasite Mermis subnigrescens¹. He found strong absorption in the blue-violet, possibly slight absorption in the ‘outermost’ part of the red, but noticed none in the orange-yellow-green. Three living specimens were kindly sent me in 1963 by Mr. J. H. Newton, of Warboys, Hunts., and I have, therefore, had the opportunity of examining the pigment again. Using a Zeiss microspectroscope, I found that, contrary to Cobb's findings, there is some absorption in the green: the pigment is, in fact, hæmoglobin. Although faint, and difficult to locate accurately, the a and b bands of oxy-hæmoglobin are unmistakably present; the wave-length for the centre of each band is about 1 mµ greater than that for the corresponding band for the human blood with which it was simultaneously compared. The identification was confirmed on sectioned material by a benzidine test² (Fig. 1).