326 THE DOMESTIC SHEEP. 



in this way that the majority of sheep and lambs become diseased. 

 To dress the pastures with fresh, air-slaked lime in the season 

 when the flocks are not pasturing is an excellent preventive 

 against all this class of parasites, and the regular culture of the 

 land, the plowing and the growing of crops in the regular rota- 

 tion; the completion of which is the seeding of the land with 

 grass and clover, will both be a help to the farmer who keeps 

 sheep, but of course of no avail to those who range their sheep. 

 These must depend on those medicinal preparations made for this 

 special purpose of avoiding these parasites, or tonic mixtures by 

 which the natural strength and vitality of the sheep may be 

 maintained, for it is the feeble and the ill-nourished that fall as 

 an easy prey to these parasites. 



OESOPHAGOSTOMA COLUMBIANUM-NODULAR DISEASE 

 OF THE INTESTINES KNOTTY GUTS. 



It ia only in recent years that this parasite has been known 

 as the cause of the disease commonly named above. Less than 



Fie. 7. a, a, Male and female, natural size; b, b, Male and female, 

 enlarged. (After Raines.) 



ten years ago it was discovered in some investigations as to the 

 nature of the knots or small tumors with which the intestines 

 of the sheep were more or less covered. This investigation curi- 

 ously enough arose from the connection of the sheep's intestines 

 with sausages. These sausage casings, of course should be perfect, 

 and above suspicion, however open to this the contents of them 

 might be. The common nodules by which these skins were more or 

 less unfitted for this use, made them unsalable, and a loss to the 

 butchers. And thus the matter became a subject of investigation 

 with the result of discovering that the disease was due to a hith- 

 erto unknown parasite of the sheep. 



The cause of this disease is a round worm, and one entirely 

 distinct from any other known species. The male is about half an 

 inch in length, the female a little longer. The head of it is bent 

 into somewhat the form of a hook. In the sheep the adult worms 

 live in the large intestine, the young ones are found in all parts 

 of the bowels encysted in small tumors, at first no larger than the 

 head of a pin, filled with a sort of cheesy matter. How the para- 

 site enters the sheep there has been no satisfactory information 

 gained so far; so that we have to deal with these facts. First 

 these nodular swellings or tumors are found on the inner walls 

 of the intestines. Of course as the walls of the intestines are 

 the absorbent organs by which the digested food is taken into the 



