68 BIOLOGY. [Book i. 



The hsematia are veritable histological elements floating in the 

 sanguineous plasma. Like everything which lives, they assimilate 

 and disassimilate incessantly. Each of them has probably only a 

 brief duration. According to the German cellular doctrine, they 

 spring in the embryon, from pre-existent cells, and multiply after- 

 wards by segmentation, by cellular division : but the point is not 

 one which direct observation has yet elucidated. It is certain, 

 however, that the hsematia are remade in the blood, for a few 

 weeks or a month suffice to cure the anaemia caused by too copious 

 blood-letting or by excessive haemorrhage. In an animal sub- 

 jected to abstinence, the globules diminish in number, lose their 

 shape, and shrink. It is probable that incessantly the more aged 

 of the hsematia dissolve in the blood, and are replaced by hsema- 

 tia of new f oi-mations. These fresh growths have their birth 

 either in the lymphatic glands, or in the special glands (thyroid 

 body, spleen, and so on). 



The physiological characteristic of the haematia is the property 

 they possess of absorbing liquids with a great energy. This 

 property is inherent in their very substance, independently of 

 their form. In efEect, a solution of this substance grows red in 

 contact with oxygen, and becomes less rutilant from contact with 

 carbonic acid. The affinity of tjie substance of the globules for 

 oxygen is quite comparable with that ■ of the green matter of 

 leaves, chlorophyll, for the carbon of aerian carbonic acid. It 

 is by reason of this powerful affinity for oxygen that in the 

 sanguineous transfusion practised in men and the mammifers the 

 injection of mere globules suffices to provoke real resurrections. 

 The blood extracted from the vessels continues to appropriate 

 oxygen and to exhale carbonic acid. From contact with oxygen 

 the hsematia swell, and tend to lose their double depression. 

 Carbonic acid, on the contrary, makes them shrink. 



In like fashion in the vertebrated organisms, the function of 

 the hsematia is to imbibe many volumes of oxygen during their 

 passage through the respiratory organs. Once impregnated with 

 oxygen, the globules give to the blood a tint rutilant, vermilion. 



