PHYSIOLOGY OF THE INVERTEBRATA. 167 



and it has nothing to do with the change in the colour of the 

 blood. 



It may be remarked in passing bhat Dr. W. D. Halliburton, 

 F.R.S.,* has shown that the blood plasma oiJIomarus contains 

 a red pigment, which is soluble in alcohol, ether, and chloro- 

 form; but it is possible that this pigment belongs to the 

 histohsematins which Dr. MacMunn has found to be pretty 

 generally distributed in the tissues and organs of the 

 Invertebrata. 



The blood of Homarus, Cancer^ Carcinus, and Asiacus does 

 not show any absorption bands when examined by the 

 microspectroscope. The blood in all these animals contains 

 hgemocyanin. 



The blood of Apus, one of the Pliyllopoda, is of a red colour, 

 and, according to Lankester, this colour is due to hEsmoglobin. 

 Another Crustacean which has red or violet blood is Gam- 

 marus. 



(6) The JPolyzoa. — Several of the Polysoa contain lipo- 

 chromes ; and in Flustra foliacea MacMunn f has shown 

 there exists a chlorophylloid pigment which is soluble in 

 alcohol. The spectrum of this pigment somewhat resembles 

 that of modified chlorophyll. The alcoholic solution is a yellow 

 colour, and has a red fluorescence. Its chief dark band reads 

 from X 681-5 to ^ 656, its darker part from X678 to A 662. 

 " It showed another before D ; the third chlorophyll band 

 was missing, and there was one lipochrome band." 



(7) The MoUusca. — The blood of many Molluscs contains 

 the pigment hsemocyanin. 



In 1 8 16, Erman simply recorded the fact that the blood of 

 ffelix was of a blue colour. Harless and Von Bibraij: (in 

 1 847) stated that the blood of Helix pomatia acquired a blue 

 colour on exposure to air, but this colour was discharged by 

 shaking the blood with carbonic anhydride. They also 



* British Medical Journal, 1885. 



t Proc. Physiol. Soc., 1887 ; and Quart. Journ. Micro. Science, vol. 30, p. 79. 



% MuUer's Archie, 1847, p. 148. 



