H. P. WOLVEKAMP 



will certainly be dealt with in the main by the Bohr effect, as a fine 

 regulation of the blood flow in animals with an open circulation system 

 can hardly be expected. 



Data on the gas-binding properties of the blood of four species of 

 ink-fishes belonging to three biological types of very different anatomical 

 build and different behaviour have been obtained, namely the American 

 squid (Loligo pealei) by Redfield, Coolidge and Hurd 1 (1926) and by 

 Redfield and Ingalls 1 (1933), the European squid {Loligo vulgaris Lam.) 

 and the cuttle fish (Sepia officinalis L.) by Wolvekamp, Baerends, Kok 

 and Mommaerts 9 and the octopus (Octopus vulgaris Lam.) by 

 Wolvekamp 10 . 



The torpedo-shaped squid is a very active pelagic animal, swimming 

 incessantly with the aid of its triangular lateral fins. The flattened 

 cuttle fish will either swim about rather slowly with the aid of its fin 

 seam, or lie on the bottom much as plaice or rays do. Octopus has a 

 bag-like body and possesses no fins. It crawls about on the bottom 

 with the aid of its arms but spends most of its time in some hiding 

 place. Moreover all ink-fishes may execute backward movements by 

 discharging a jet of water from the mantle cavity, by way of the so- 

 called funnel. Squids and cuttle fish cover considerable distances 

 during their migrations to and from their spawning places. 



The oxygen dissociation curves of Octopus blood are, in the absence 

 of carbon dioxide, very steep. The displacement of the curve at 

 moderate carbon dioxide tensions is considerable. The affinity of the 

 haemocyanin in the blood of Sepia is of the same order of magnitude 

 as in the blood of Octopus, but the Bohr effect is much more pro- 

 nounced. In the European squid the affinity for oxygen is somewhat 

 lower and the dissociation curve is more inflected. There is a large 

 shift to the right of the oxygen dissociation curve, even at very small 

 partial tensions of carbon dioxide. The affinity for oxygen of the 

 blood pigment of the American squid is small and the Bohr effect may 

 be called excessive (Figure 6). It is fairly clear that the squids, and 

 specially the American species, will be able to five in well aerated water 

 only, but Octopus, which often hides in narrow caverns, can stand 

 lower oxygen pressures. Sepia would occupy an intermediate position. 

 On the other hand the enormous Bohr effect will greatly enhance the 

 acquisition of oxygen by the tissues in the squid. Generally speaking 

 there is a correlation between the gas-binding properties of the blood 

 and the way of living. 



Simple inspection of the blood vessels of the gills in an animal whose 

 pallial cavity has been exposed by a slit in the mantle, while a strong 

 jet of water is directed on the gills, shows that the dark blue blood 

 leaving the gills has become colourless before returning through the 



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