ELEMENTS OF COMPOSITION. 



19 



subsequent thawing of blood ; by elevation of temperature to 60 C. ; by 

 electric discharges and the continuous current ; by pumping out the gases 

 of the blood; by the addition to the latter of various salts, such as 

 sulphate of soda and those of the bile ; and by the action of chloroform 

 with free access of air. The blood of different animals crystallizes with 

 varying degrees of readiness. In that of the guinea pig crystals are 

 formed particularly rapidly. The blood of the splenic vein is also remark- 

 able above that of all other 

 localities for the freedom with 

 which crystals are formed in it. 



There appear to be further 

 several kinds of haemoglobin 

 in the animal kingdom. 



In the reddish blood of many 

 of the invertebrate animals 

 haemoglobin has also been 

 found. 



The colouring matter of 

 muscle is identical, according 

 to Kiihne, with that of the 

 blood-corpuscles. 



Blood-crystals are met with 

 under various forms such as 

 prisms, tetrahedrons, hexagonal 

 tables, andrhombohedrons. The 

 first is by far the most univer- 

 sally encountered, appearing in 

 man and the greater number of 

 mammals (tig. 1, c), in which 

 rhombic tables may also occur f^^ 



(b). The haemoglobin of the f \^J 

 mouse and guinea pig assumes ^-^ 



(& 



Fig. 1. Crystals from the blood of man and some mam- 

 mals, a, blood-crystals from human venous blood; 

 6, from the splenic vein; c, crystals from the blood of 

 a cat's heart ; d, from the jugular vein of a guinea 

 j>ig; e, from the hamster; and/, from the jugular vein 

 of the squirrcL 



f ^ > 



the form of tetrahedrons (d). 



Hexagonal plates have up to 



the present been found in the 



blood of the squirrel only (/). 



In the hamster or German 



marmot we find rhombohedrons 



(e). In fact, almost all blood-crystals belong to the rhombic system, 



with the exception of those of the squirrel, which. belong to the hexagonal 



(Rollet, von Lang). 



Haemoglobin, crystals are double-refracting and pleochromatic ; observed 

 in one aspect they are bluish-red, in another, scarlet. 



They are insoluble in ether and alcohol, but dissolve in water, com- 

 municating to it a blood-red tint. 



"Watery solutions of haemoglobin coagulate on being heated, owing to 

 the production of an albuminous substance globulin, and haematin to be 

 mentioned below. The same separation is brought about by the action 

 of acids and alkalies. 



Haemoglobin combines with many gases, e.g., oxygen, carbonic oxide, 

 and nitrous oxide. Crystals obtained under free access of air con- 

 tain oxygen in loose chemical combination, which is parted with in a 

 vacuum, or when the former are heated. This is the oxylieemoglobin 



