— 89 — 



Haemoglobin coiitaiiis iron in its moleculc; wliilc copper occurs 

 in tlic molecule of haemocyanin: tliis isalready a fundaineiital dif- 

 ference between Illese two oxygen-cniriers. Haemoglobin may he 

 split up in two siniplcr dissociation-products: globin, an albumi- 

 nous, iron free, histone-like substance and the " prosthetic " group 

 haeniatin, \xliich contains ali the iron of the haemoglobin. An 

 analogous dissociation of haemocyanin has not yet been accom- 

 plished, as haemocyanin very easily lOses its copper. Copper is 

 found in haemocyanin as a very labile complex ion , and does 

 not give aiiy copper-ions reaction. Traces of minerai acids are 

 sufficient to liberate the copper as ionizable copper salt. 



Different haemoglobins are known and very probably, diffe- 

 rent haemocyanins exist. The data fiirnished us by the various 

 authors on haemocyanin do not always agree, a fact which vcould 

 lead one to believe that they bave had to do with different haemo- 

 cyanins. Alsbero and Clark (2) bave already drawn attention to 

 the difference between the haemocyanin. of Ll/niilus Polyphemus 

 and that of Octopiis viilgaris. This difference becomes stili more 

 evident on comparing the analysis of the haemocyanin of Li- 

 mili us Polyphemus, made later on by van Slyke (3), with Henze's 

 analysis (5) of the haemocyanin of Octopus viilgaris. 



Later Dèhré (8) has begun to investigate the question of the 

 diversity of haemocyanins by comparing their spectra and their 

 behaviour to dialj'sis and to the biuret reaction. 



Haemoglobin crystaliizes more or less readily according 

 to the animai to which the blood belongs. Different crystalline 

 forms of haemoglobin are known; the shaj^es may vary with the 

 different animals and may also undergo a change on recrystalli- 

 zat-ion. The opinions of the authors are divided as to whether 

 this fact denotes a change or a difference in the structure of the 

 molecule. Haemocyanin may also cristallize in different forms as 

 will be seen later. 



I intend to study more minutely the haemocyanin of the 

 different blue-blooded animals to be found in the gulf of Naples, 

 and to show up the chemical and physico-chemical analogies and 

 differences existing between them. 



This paper will tieat of the crystallization of the haemocya- 

 nin of Octopus vulgaris, Octopus macropus and Eledone moscliata. 



