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hao X strong stiinulating effect on the braiicliial hearts and on 

 the ventricule. 



I have been able to collect, in this way, more than two h- 

 ters of hquid which is, naturahy, sea-water faintly coloured in blue 

 by a very slight quantity of oxyhaemocyanin. If the animai is 

 held under t!ie water; preventing the jet of water to fall on the 

 incision, the blood conies out without any mixture of sea-water. 

 When water is allowed to fall on the incision, the haemocyanin 

 content of the flowing blood, naturally, diminishes rapidly, and 

 finally disappears altogether. It is a good idea to adopt this 

 method when blood is collected for haemocyanin preparation , 

 because in this way a sort of self-washing of the blood vessels 

 is obtained, and consequently the greatest possible quantity of 

 haemocyanin that the animai can yield, is obtained in the shor- 

 test space of time and without any further technical complication. 



The blood is left to stand until the wliite corpuscles have 

 collected on the bottom; it is then filtered directly or afferà pre- 

 vious centrifugalization. In this way the blood may be preserved, 

 for a ratìier long time, without the addition of an antiseptic. 



Oxygenation of the blood. 



When the animai is out of water, the blood in the artery 

 becomes discoloured as it loses its oxygen, but on -being immer- 

 sed again in the water it recovers its naturai dark blue colour, the 

 reduced haemocyanin being tlius oxygenized to oxyhaemocyanin. 

 For the present researches it matters very little whether the blood 

 runs off oxygenized or no, as it may be easiiy reoxygenized by 

 shaking it with air. Another simple means to oxygenize it is by 

 filtering. It is sufficient to pass it through tlie pores of the filter 

 paper in order to get the dark blue colour which is the surest 

 sign of speedy oxygenation. 



On using a ruied filter paper which has a greater filtering 

 surface, or on filtering it successively through several filters pla- 

 ced one above the other so that the oxygenation begun in the 

 first may be completed in the others, oxygenation is perfect. In 

 this method may be found a praticai explanation of the process 

 of oxygenation of the blood in the gills. 



