119 



Whatever changes the embryos may pass through outside the sheep 

 can have little to do with the case as far as a knowledge of prevention 

 of infection goes, for but very few of the conditions under which these 

 sheep were kept can be improved by the flock-master. 



Disease. — The tape-worm disease can be diagnosed by finding the lit- 

 tle white oblong tape-worm segments which are voided from the sbeep 

 and stick to the moist pellets of dung. They may also be found adher- 

 ing to the wool and dirt around the tail. But this is only after the 

 tape-worms have become adult and have begun to shed segments. 

 Though sheep often harbor tape-worms and give no evidence of their 

 presence until after slaughter, there are other cases in which their pres- 

 ence is only too evident to the flock-master. The first indications of 

 the disease are usually unobserved, because of the slow growth and of 

 the comparatively small number of parasites that may be developing. 

 The time of growth occupies about two or three months from infection. 

 The number of individuals maybe from two or three to a hundred, but it 

 is unusual to find more than a half dozen adults together. As many as 

 fourteen adults were found in a lamb four months old. When young 

 they occupy but small space, need little food, and cause few vermicular 

 contractions. In the earlier stages it is plain that they cause but little 

 trouble, but when they grow so large that they seem to fill the whole of 

 the small intestines they cause the serious disturbances ascribed to them. 

 These disturbances may be to a certain extent those arising from a re- 

 flex irritation of the sympathetic and spinal nerves, but most of them 

 seem to be due to the indigestion which the worms produce. The worms 

 obstruct the iutestinal canal by their great mass, irritate it by their ver- 

 micular contractions, cause excessive secretion of intestinal fluids, non- 

 assimilation of food, and abstract nutriment from the iutestinal con- 

 tents for their own growth. 



The lambs become poor and hidebound; their flanks may either be 

 distended by gas in the bowels or be tucked up from gauntness. 

 lu the progress of the disease the animals become evidently weaker, 

 the mucous membranes paler, and the fleece dry and harsh from the 

 loss of its yolk. The animals walk with a tottering gait. They often 

 eat more and drink oftener than those less affected. In the severest 

 cases the lambs grow extremely weak and poor, diarrhea becomes inore 

 and more pronounced,, and at last thej"^ die through sheer exhaustion. 

 While suffering from these worms they are more susceptible to the at- 

 tacks of other parasites, and other diseases supervene and hasten the 

 death of the ali-eady weakened animals. 



Prognosis. — Though the tape-worm disease in its mildesfform is very 

 destructive to lambs and yearlings, yet it would seem that if they are 

 able to pass safely through a certain period they are very apt to re- 

 cover. In 1887, in the examination of two wethers which two weeks 

 before had been passing proglottides, or segments, in abundance, and 



