156 Disturbances of the Blood. 



lymphglands, where they may perhaps multiply and give rise to 

 suppuration ; thence they may travel from one lymph node to 

 another (retropharyngeal, cervical, thoracic), in each setting up 

 new foci of suppuration, until they finally reach the blood and pro- 

 duce pyaemia. 



No matter how minute the lesion of the skin or mucous mem- 

 brane, infectious bacteria may from some source gain access to 

 the lymphatic radicles and occasion their specific processes in the 

 lymph channels and at their points of deposit in the lymph glands 

 (cf. tuberculosis and carcinoma). Lymphogenous extension or 

 embolism is therefore to be regarded as an important factor in the 

 generalization of local infectious processes. 



Pathological Changes of the Blood. 



The blood supplies the tissues with the oxygen essential to their 

 life, besides the albuminates, carbohydrates and water ; it removes 

 their metabolic products and is the principal factor in the distribu- 

 tion of heat; it, therefore, maintains the functions of the nervous 

 system, the heart and all of the organs as their liquid nutrient, their 

 source of heat and their cleansing fluid. In its manifold relations 

 to the tissues, in its function of giving and receiving on so many 

 sides, there arises constant change in the quantity and composition 

 of the blood, limited, of course, within certain bounds and relations 

 set by the tissue requirements. When blood is lost, fluid is taken 

 into the vessels from the tissues and corpuscles are supplied by the 

 blood forming organs to the eventual restoration of the blood. 

 When an excessive amount of water is absorbed there follows rapid 

 excretion of the superfluous quantity through the kidneys ; and in 

 analogous fashion the variations in its chemical constitution are 

 continually undergoing adjustment. \\'e have yet to discover 

 wherein lies the exact and delicate regulation of the quantity and 

 quality of this complex liquid ; at all events the changes -in 

 chemical composition involve continually repeated stimulation of 

 the nerves of the blood vessel walls, of the cells of the hgemopoietic 

 organs and all secretory cells upon which the hremic composition 

 depends. As soon as this regulation is disturbed the variations 

 in the volume and proportionate composition of the blood deviate 

 from the physiological limits, and hcxmic anomalies* are said to 

 exist. 



*The word ili/scrasia was formerly employed in this connection, but was wittiout 

 exact significance, being applied by some to any blood abnormality, by others to long 

 persisting faults in the proportionate presence of its constituents or simply to 

 impurities of the blood from the presence of special substances. The word may be 

 dispensed with. 



