DISEASES OF THE OX AND SHEEP. 599 



which traverses and penetrates it. The muscle-wave commences 

 in the field of innervation, and has indeed been actually fixed by 

 sudden hardening of muscles. Du Bois-Reymond has been 

 able with the galvanometer to render the excitation of nerves, 

 not attached to muscles or ganglion-cells, evident as the nega- 

 tive variation of the natural nerve-current, to cause movement 

 of a magnetic needle instead of a muscle, or to put the move- 

 ment of the needle in the place of sensation. The currents of 

 action of muscle were a long time ago proved to excite nerves, 

 and there are similar effects from nerve to nerve, Kiihne 

 has succeeded in practically uniting two muscles, the nerves 

 of which had been poisoned by curare, so that they acted as 

 one. Stimulation and contraction were propagated from one 

 end to the other. Any electrical insulation stopped the 

 current, and hence the first muscle must previously have excited 

 the second electrically. It seems, then, that muscle is ordinarily 

 excited by actual electric currents, and not merely by forces 

 resembling electric currents. 



RHEUMATISM IN SHEEP. 



We include, perhaps not altogether correctly, rheumatism 

 in this group of disorders of the organs of locomotion. Rheu- 

 matism usually breaks out in sheep in consequence of careless 

 and cruel exposure of these animals to wet and cold weather. 

 As might be expected, the disease is markedly prevalent in 

 low-lying, marshy districts, and, in fact, in all exposed situations; 

 and it is most generally met with in inclement and tempestuous 

 weather. In the general way it attacks old sheep or very young 

 ones. Occasionally rheumatism may manifest itself in an acute 

 form, when it is attended with severe febrile symptoms. More 

 usually the malady is chronic in character, and the walk may 

 be noticed to be stiff and cautious. If this is the case, the 

 disorder is not often completely eradicated. 



We have previously considered somewhat in detail the disease 

 known as foot-rot. Now, in addition to this affection of the 

 organs of locomotion, there are two others connected with the 

 same mechanism of locomotion which require a brief description 

 at our hands. These are arthritis or joint-ill, and rickets. We 

 also propose to discuss briefly a lamb-disease which broke out in 

 America in the spring of 1862. Possibly it was nephritis. 



