482 
C. A. MAC MUNN. 
result obtained being negative, so far as hsemochromogen is 
concerned. The pigment present in them is closely related to, 
if not identical with, tetronervthrin, and in the hypoderm of 
Cancer pagurus and integument of U raster rubens, where 
I have shown tetronerythrin 1 to be present, the solid pigment 
gives the same kind of band. In some Serpulae I could per- 
ceive the bands of the colouring matter of the blood itself in 
the gills. The tetronerythrin of the gills and other red parts 
is probably of no respiratory use, and I think its action with 
reducing agents in other cases goes to show that too much 
importance has been attached to its supposed respiratory func- 
tions. It is not unlikely that, especially when its likeness to 
Kuhne’s chromophanes is taken into consideration, it may be of 
use in absorbing certain rays of light concerned in some obscure 
photochemical process. 
The colouring matter of the perivisceral fluid of 
Strongylocentrotus lividus. In 1883 2 I stated that in 
various parts of the body and in the perivisceral fluid of 
Echinus (esculentus ?) and sphaera I had detected a colour- 
ing matter of a brown colour which gave two bands, one 
between D and E covering E, the other between b and F, the 
first of which became decidedly darker with ammonium 
sulphide. I found that it went into chloroform and alcohol, but 
owing to a dearth of material I did not arrive at any very definite 
conclusions, except that this pigment is respiratory. Professor 
Schafer informed me some time after the publication of these 
results that in working at the coagulation of the perivisceral 
fluid of an Echinus he had seen the same bands ; and P. Geddes 3 
had observed the colour changes of a similar pigment. The 
latter observer has worked out the morphology of the cor- 
puscles of the perivisceral fluid of various Echinoderms 4 and 
1 ‘Proc. Birm. Philos. Soc.,’ vol. iii, 1883. 
• ‘Proc. Birm. Philos. Soc.,’ loc. cit., pp. 380, 381. 
3 See Gamgee’s ‘Physiological Chemistry,’ pp. 134, 135. 
4 ‘ Proc. Roy. Soc.,’ No. 202, 1880. I have not seen his paper 
‘ Archives de Zoologie Experimentale.’ 
