THE DIGESTIVE SYSTEM. 257 



sence of disease of the reticulum. Elimination of gas in 

 the rumen always occurs to a certain extent. The causes 

 of excess in this matter are either dependent primarily on 

 the state of the stomach or on the nature of the ingesta. 

 Fresh green food^ introduced in too large quantity, un- 

 dergoes fermentation, for it is placed under conditions 

 favorable to that process — a temperature of about 100° and 

 moisture. Thus, in the earliest stages, carbonic anhy- 

 dride is the gas given off ; but if these matters remain too 

 long in the stomach they decompose, and then sulphuretted 

 hydrogen is eliminated. Probably this gas is given off 

 in extreme quantities at once, after ingestion of rotten 

 turnips. Considering the conditions of the full rumen, 

 fermentation must occur in it if its contents are not ex- 

 pelled in due course so that only a small quantity remains, 

 since it seems the organ must never be thoroughly emp- 

 tied. This residuum, however, is subject to almost 

 perfect renewal with each digestion in consequence of 

 the churning action, which ensures thorough intermingling 

 of the gastric contents. 



Torpidity of the rumen occurs in debilitating diseases — 

 in fact, in most disorders of the ox ; also from introduc- 

 tion of excessively cold material, as turnips which are 

 frosted, and grass covered with hoar frost. The gas can 

 escape in two ways — through the oesophagus or through 

 the omasum — but this may be prevented by oesophageal 

 spasm — or by contraction of the rumino-reticular sphincter. 

 The latter probably occurs as a result of ingestion of cold 

 food, but when green food has been passed into a torpid 

 rumen this probably accumulates unduly about the opening 

 of the first and second stomachs, and thus prevents both 

 the ingress of medicaments and the egress of gas from 

 the deeper parts of the cavity of the rumen. In some cases 

 of difficult parturition considerable hoven is present, and 

 delivery does not take place until this state is relieved. 



Treatment. — The practitioner called in to a case of 

 hoven probably finds the animal in danger of suffocation 

 from extreme abdominal distension. When a fatal result 

 threatens every minute it is generally advisable to 



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