— 90 — 



The crystalline forms will be illustrated by microphotographs 

 of the undenaturahsed crystals. 



Before describing the method followed for the crystalhza- 

 tion of the haemocyanin I shall first describe the maiiner in whi- 

 ch theblood was taken from the animals. 



The blood was obtained in the way already described by Fre- 

 DERiCQ (1), and followed by almost ali the other workers. 



The animai was nailed back upwards to a board; by making 

 an incision in the back, the cephalic aorta is easily found. It is 

 rather large, and is characterized by its blue colour due to the oxy- 

 haemocyanin contained in the blood. The attery, in the proxi- 

 mity of the head, was cut in two and tlie part next the head tied- 

 a cannula was inserted in the other part i. e. in a centrai direction, 

 so that the blood niight flow freely in the direction of the circiila- 

 tory current; this is made easier by the high arterial pression 

 under which the blood circulatcs in these cephalopods '). The 

 board with the animai attached was immersed in a tank containing 

 running sea-water. 



Self-washrng phenomenon. 



I will observe here that if a jet of sea-water is allowed to 

 fall on the incision, the blood begins to flow rapidly from the 

 cannula as if from a tap, It would seem, therefore, that the water, 

 under the pressure, however slight, of the jet, penetrates in the 

 venous sinus, from which it passes to tne branchial hearts and from 

 thence, following the nornial circulatory course through the gills, 

 reaches the ventricule by which it is driven out. This view would 

 be supported by the following experiment: on tying the two affe- 

 rent branchial vessels at the base of the branchial hearts, the liquid 

 ceases to flow out although the jet of water continues to fall on 

 the incision; but on freeing one of the afferent veins or both, 

 the liquid begins to flow again. It is very probable that sea-water 



') By iising a nierciiry manometer, the niaxiinuin arterial blood pressure 

 was found to be resp. iS4, 84, 66, ISi, 87, 130, 9i3 and 64 mms. Hg in Octo- 

 pus valgaris; and 98, 90, 110, 116, 108, 88,. 108 and 80 mms. Hg in Octopiis 

 macronus. (Author's researclies not yet publislied). 



