158 Disturbances of the Blood. 



peculiar phenomena in these instances, which have thus far been 

 imperfectly studied ; for example, the red blood corpuscles may 

 undergo reduction and disintegration because the plasma contains 

 some unusual saline or an excess of water or because some spe- 

 cific hgemolytic substance has become mingled with it. Briefly 

 speaking, it is customary to speak of general anaemia in a subject 

 whose mucous membranes and skin persistently appear very pale, 

 whose muscular tissue and viscera have at autopsy the pallor char- 

 acteristic of a slaughtered animal and in which in life there ex- 

 isted a condition of general weakness. The contrast between 

 the peculiar tint of the organs and the deep red color given by the 

 full capillary blood serves better to indicate the reduction in the 

 volume of the blood than the amount which can be obtained in 

 the heart and large vessels and which can be estimated only with 

 extreme difficulty. Oligocythsemia is determined for a cubic milli- 

 meter of blood by microscopic counts of the cells with special 

 measuring apparatus; diminution of the hsemoglobin content can 

 be determined only by chemical methods. [Clinically this latter 

 is estimated by comparison of either the whole or the diluted blood 

 with standard color scales, each graduation of tint representing 

 a certain proportion of hsemoglobin. Matching of colors always 

 involves a large personal equation and at best can only be approxi- 

 mate, even were it established that the supposedly standard refer- 

 ence scale were entirely correct — which is not the case. How- 

 ever, as an approximation only and as a fairly ready means of 

 comparison, these color tests have at least a clinical value.] 

 The least complicated form of oligjemia is that occasioned by 

 blood loss from injury to the vascular apparatus, hcemorrhagic 

 anccmia, following wounds and lacerations of the vessels, venesec- 

 tion or the removal of blood by blood sucking parasites. A blood 

 loss exceeding three per cent, may be dangerous to life (external 

 or internal injuries) and sudden haemorrhages of still smaller vol- 

 ume from the large vessels may be fatal. [While exceptionally 

 this statement may be true where there are other factors as nerv- 

 ous shock involved, the limits of non-fatal blood loss as here given 

 are for ordinary cases quite too low. As much as one-third the 

 volume of blood has often been withdrawn without fatal collapse.] 

 The volume of fluid lost by non-fatal hgemorrhage is soon 

 restored by absorption of water from the tissues and ingesta ; while 

 the corpuscles and albuminous material are reformed in the course 

 oi a few weeks or months. In fatal haemorrhage there occur 



