BLOOD. 307 



This form of diseased blood appears capable of being subdivided 

 into two classes : one embracing diseases primarily dependent 

 upon the chylopoietic viscera, such as are due to bad food, de- 

 ficient and improper formation of chyle, atmospheric influences, 

 protracted action of poisonous mineral agents (lead, mercury and 

 its compounds, chlorine, iodine, &c.) ; and finally, to inordinate 

 consumption of the blood through a deficiency of the animal fluids. 



The corpuscles, which, as we have seen, are of the utmost 

 importance in the blood, are either not produced in suflicient 

 quantity, or are consumed in a quicker proportion than they are 

 reproduced. The liquor sanguinis, although poor in fibrin, may yet 

 contain a sufficient quantity of albumen and salts to prevent the re- 

 latively increased quantity of water from dissohdng the corpuscles. 



All the diseases arranged by Schonlein under the family 

 cyanoses belong to this subdiAdsion. 



The other subdivision embraces certain diseases characterized 

 by the peculiar composition of the blood, but in which the pri- 

 mary causes of its change of composition are quite distinct from 

 those which act in the cyanoses, and are probably dependent 

 upon the central nervous system. A peculiar state of the at- 

 mosphere (most likely due to certain changes in its chemical 

 composition), protracted wars, the efiluvia of decaying animal 

 matter, &c., are assigned as the external causes of the production 

 of these disorders, the principal of which are abdominal typhus, 

 petechial typhus, the yellow fever, and the plague. 



In the cyanoses, as also in the malignant (putrid) form of 

 typhus, passive hemorrhages are by no means rare. 



It has been asserted that the deficiency of fibrin and of cor- 

 puscles renders the blood liable to exude through the Avails of the 

 vessels. It is clear, however, that the colouring matter cannot 

 escape through the walls of the capillaries, unless such a change 

 occurs as to render the hsematoglobulin soluble in the liquor 

 sanguinis, since perfect corpuscles are not capable of passing 

 through the uninjured walls of the vascular system. As the blood 

 which is discharged by epistaxis in the morbus maculosus Werl- 

 liofii (as Avell as menstrual blood) contains corpuscles, the walls 

 of the vessels must be imperfectly closed. Such a form of blood 

 appears to occur in the putrid form of abdominal or petechial 

 typhus. The haimatoglobulin becomes soluble in the liquor 

 sanguinis, in consequence of a deficiency in the due proportion 



