DISEASES OF THE OX AND SHEEP. 473 



to lambs, the latter suffered from gid. In one experiment 

 it was found that even a fourth part of one hydatid of a 

 sheep led to the development of one hundred and ninety-one 

 tapeworms in a dog. These tapeworms grow so as to be one 

 line or two in length in less than a fortnight ; by the third week 

 they become an inch long, by the fourth week about four inches 

 long, and finally, at the close of the third month, they may be 

 about two and a quarter feet long. These tapeworms remain in 

 the small intestines of the dog; but when they are about to 

 be expelled in part, they extend, of course, into the large 

 intestine. 



One of the chief points about them is that they are liberated 

 in separate portions called segments or proglottides, each one of 

 which is charged with many hundred eggs. Hence it will be 

 readily seen that the risk of some of the eggs being swallowed 

 by sheep is very greatly intensified by the fact that a dog may 

 distribute these joints in many different parts of a field. By 

 way of experiment, proglottides of this tapeworm were given to 

 thirty-nine sheep and two calves, with the result that twenty- 

 two became affected with sturdy. Naturally, we should not 

 suppose that all would take the disease, since in some cases the 

 eggs would perhaps pass harmlessly along the course of the 

 digestive canal without any deleterious effect whatsoever. 

 Moreover, the joints or segments must be mature, in order to 

 produce any effect. 



In the cases we are speaking of, the symptoms were manifested 

 from about a week to about four months after the proglottides 

 had been swallowed. The number of coenuri found in the brain 

 varied from four to about two hundred, and they were as a rule 

 distributed throughout the brain. It is noteworthy, too, that 

 the cysts are frequently found in the muscular tissue, and 

 «specially in that of the oesophagus, intestines, diaphragm, 

 and heart. As is very evident, the symptoms displayed by sheep 

 afflicted with the malady entirely depend upon the number and 

 position of the hydatids in the brain. 



It is manifest that the effects on the nervous system of the 

 animal must be dependent on the number, size, and position of 

 the cysts. In the early stages the disease may be only very 

 slightly observable. The afflicted sheep has a dull appearance, 

 turns round and round, and often falls down, will not graze. 



