PHYSIOLOGY OF THE INVERTEBRATA. 143 



that the blood of Crabs and Oephalopods on treatment with 

 carbonic oxide became colourless, but regained its blue colour 

 on shaking with air. This behaviour is different from that 

 of hsemoglobin when similarly treated. It was further found 

 that blood which had become blue by the reception of oxygen 

 if allowed to stand in a test-tube exposed to the air did not 

 lose its blue colour from above downwards, but from below 

 upwards, whence he concludes that the blueing is not due to 

 suspended particles, but to the presence of a chromogen 



which becomes blue by the reception of oxygen He 



could find no hsemocyanin in the blood of several Molluscs 

 (&.g., Tetliys fimbria, Boris tuberculata, Aplysia depilans, 

 &c)." 



Although the blood of the higher Invertebrates, as a rule, 

 contains copper, in some this element is replaced by man- 

 ganese. Krukenberg has shown that the blood of Pinna 

 squamosa (one of the Lamellibranchiafa) as well as the organ 

 of Bojanus are rich in manganese. If a borax bead is dipped 

 into the blood of Pinna and then heated in the oxidising 

 blowpipe flame, the bead becomes a distinct violet colour, and 

 in the reducing flame it remains colourless. 



It is probable that copper, manganese, and possibly other 

 metals play the same part in the blood of the Invertebrata as 

 iron plays in the Vertebrata. 



The author* of the present volume has also extracted 

 copper from the blood and organs of Sepia officinalis ; but the 

 process was entirely different from those of Predericq and 

 Krukenberg. 



In the majority of the Invertebrata the carrier of oxygen 

 to the tissues is hsemocyanin contained in the blood ; but in 

 many of the Annelida, as well as in nearly all Vertebrates, 

 the transport of oxygen from the surrounding medium (air 

 or water) to the living tissues is made by means of the 

 haemoglobin of the blood. 



* See Dr. Griffiths' paper in Chemical News, vol. 48, p. 37 ; Journal of 

 Chemical Society, 1884, p. 94. 



