Hcemoglobin&mia. — Azotemia, Etc. 457 



The rnicrobian doctrine of causation is virtually disproved by 

 the absence of all evidence of contagion, and by the encreased 

 susceptibility left after a first attack. It is a common experi- 

 ence that one horse only out of a stable falls a victim, and 

 though he may have later attacks, under the usual conditions of 

 high feeding and condition, interrupted by a short period of 

 idleness, and followed by a resumption of work, yet there is no 

 evidence of an encreasing tendency to the disease on the part of 

 the other horses as would happen with a contagious microbian 

 affection. The remaining debility of the nerve centers after a 

 first attack, or even the continued presence of a streptococcus and 

 its toxins, might easily encrease the susceptibility to a second 

 attack, without requiring us to subscribe to the apparently un- 

 tenable position, that this is the essential cause of the disease. 



Lesions. These are especially found in the blood, liver, spleen, 

 muscles, bone-marrow and kidneys. The spinal cord and nerve 

 trunks are occasionally affected. 



The blood is charged with carbon dioxide and is black, tarry, 

 comparatively incoagulable remaining in the. veins and showing 

 an irridescent reflection. It does not absorb oxygen readily 

 though exposed to the air, and thus bears a strong general 

 resemblance to the blood of anthrax. It contains an abnormal 

 proportion of urea and allied extractive matters which greatly 

 increase its density, and interfere with the healthy exercise of 

 the different cell organisms and fnnctions. These are not due to 

 excessive muscular activity as stated by Friedberger and Frohner, 

 but are derived mainly from the abundant products of digestion. 

 When the shed blood coagulates it forms a soft clot without buff 

 and the expressed serum is reddish from the presence of haemo- 

 globin, and of hsematoidin crystals. The uncoagulated blood 

 drawn over a sheet of white paper stains it deeply by reason of 

 the same coloring matters in solution. The red corpuscles may 

 be paler than natural, some even entirely colorless, and they are 

 often notched or broken up in various irregular forms. They 

 have lost the natural tendency of the shed equine blood to stick 

 together, to collect in rouleaux and precipitate to the bottom of 

 the vessel, so that no buffy coat is formed, should the blood 

 coagulate. The white corpuscles are relatively increased. Finally 

 the coloring matters contained in the plasma are imbibed by 



