DR. C. A. MAC MUNN OX MYOH^MATIN AND THE HISTOHiEMATINS. 271 
seen, differing from that of the mantle in this that the two second bands are fused 
into one. (See Chart I., spectra 5 and 6.) In the heart there is an attempt at a 
myohsematin spectrum. In the gills, and in the adductor and retractor muscles, faint 
bands may be seen in some specimens belonging to the histohsematins. 
In Ostvcea edulis the fleshy abdomen gives a distinct, though faint, histohsematin 
spectrum :—a faint band before D, and another in green like the first band of hsemo- 
chromogen. On treatment with sulphide of ammonium the spectrum is better defined. 
On examining two or three thicknesses of mantle placed over each other a similar 
spectrum is seen. A similar pigment occurs in the gills, only that the band before D 
is invisible. In the stomach wall, intestine, and in the adductor muscle we meet with 
similar appearances. It requires a practised eye to recognise these bands with 
certainty. 
In other lamellibranchiate mollusca, such as Unio and Anodonta, histohsematins 
occur especially in the foot, but it is in the pulmonate mollusca that their spectra are 
most distinct. Just as in birds and in insects, where respiratory activity is greatest, 
we find the myohsematin spectrum best marked, so in the air-breathing mollusca the 
histohsematins are better marked than in other members of their sub-kingdom. It is 
worthy of notice that in Helix, Limax, Avion, and others the “ bile ” contains entero- 
hsematin, and that in Limax and Avion, just as in Uvastev vubens, the integument can 
be made to yield hsematoporphyrin as I have shown.* I think here, too, there can 
be little doubt that the histohsematins are the mother substance of the in tegumental 
hsematoporphyrin. In the heart of all the pulmonate mollusca and in their buccal 
muscles myohsematin occurs, as will be shown further on. 
In Helix aspersa (besides the heart and pharyngeal muscle) spectra are perceptible in 
the davtsac, in the ovo-testis, vas deferens, albumen gland- in the foot, in the wall of 
crop, in the veceptacidum seminis, in the oviduct, in the penis, in the neplvvidium, and 
in the finger-shaped gland (Claus). In most of these a faint band before D occurs, 
and either one broad band occupying the position of the second and third myohsematin 
bands, or one or two faint bands resembling and placed nearly in the position of those 
of hsemochromogen. The spectra correspond so closely with those seen in Limax that 
those figured for Limax will illustrate the above. 
In the veceptapulum seminis of one Helix a redder portion was visible, which showed 
spectrum 7, Chart I., and which is remarkable for its likeness to methsemoglobin. In 
the nephvidium the spectrum was well marked, and either showed a feeble band before 
D and a broader and darker one between D and E, spectrum 8, Chart I. (from Limax), 
or two narrow bands in green closely resembling the second and third of myohsematin 
(spectrum 9, Chart I.). 
In Helix pomatia similar spectra can be observed. In the foot a band, or sometimes 
two, corresponding to those of hsemochromogen, are visible ; a similar spectrum in the 
davtsac, and similar spectra in the same parts as those in Helix aspersa. Limax 
* Proc. Birm. Phil. Soc., loo. cit., and Journ. of Physiology, vol„ vi., p. 38; vol. vii., pp. 2t0—252. 
