Impactio)i of the Omasum {Third Stomach) . 125 



nioveuients of the first two stomachs but not of the third by 

 electric stimulation of the vagus, while the third stomach was 

 excited to action by excitation of the spinal cord and of tlie sym- 

 pathetic twigs proceeding from this to the manifolds. Ellen- 

 berger indeed avers that the walls of this viscus are abundantly 

 furnished with ganglionic cells which are called into action b\^ 

 this sympathetic stimulus. The innervation being derived from 

 an independent .source, derangement of the third .stomach may be 

 quite independent of any primary disorder of the first, and the 

 omasum deriving its motor supply from sources so closely related 

 to the va.so-motor ones, may give an additional explanation of 

 the intimate connection of its disorders with febrile and inflam- 

 matory diseases. 



But while acknowledging the controlling influence of torpor or 

 paresis of the omasum, it would be an error to follow Cadeac in 

 denying the influence of food as a cause of impaction. It has 

 long been notorious that impaction of the omasum is preemi- 

 nently a disease of winter, or of the period of dry feeding. It 

 occurs in cattle fed on dry, fibrous, innutritions fodder, and es- 

 pecially when there is a scarcitN^ of water, or when in connection 

 with severe frost the usual water supply has been frozen up. It 

 prevails in stock turned in spring or autumn on pastures in 

 which the fresh green grass grows up among the dead, dried and 

 withered stems of a previous growth and tempts them to eat them. 

 It appears when the stock consumes corn or cornstalks affected 

 with .smut or certain other fungi, or the cereals or grasses suffer- 

 ing from ergot or smut, but this is especially the case when there is 

 also a privation of water, whereas, with an abundant water supply 

 or a partial ration of roots, potatoes or ensilage the danger is 

 greatly reduced. vSometimes a change from soft to ver}^ hard 

 water appears to act as a cause but whether from a special a.strin- 

 gent action or a disinclination to consume the usual amount has 

 not been made clear. 



It nuist be allowed that the sheep and goat which habitually 

 drink little, suffer far less from this affection than the ox which 

 drinks freely, yet allowance must be made for the con.stitution 

 and long settled habits of the genus, and we must not forget 

 that it is usually under privation of water or a restricted supply 

 that the ox suffers. 



