1907.] on Certain Seasonal Diseases of the Sheep. 551 



peritoneal liquid may be clear and limpid, and not show any of the 

 organism until after being incubated. These cases run a chronic 

 course, and in them the nervous phenomena are most marked. The 

 difference between the acute and the chronic case seems to depend 

 upon the rapidity and volume with which the bacillus gets through 

 the intestinal wall. In the chronic case the number is evidently 

 small, and can be dealt with by the solvent action of the blood, 

 while in the acute case the number is so great that the animal dies 

 from rapid toxic poisoning. All seems to depend upon the condition of 

 the blood. If it be in its usual state of antagonism to the growth of 

 the bacillus, such as prevails during the greater part of the year, 

 apparently the bacillus cannot leave the cliannel of the bowel. If, 

 on the other hand, this salutary property be weakened but not 

 annulled, a certain leakage as it were takes place, but still the number 

 of bacteria which find entrance to the blood-stream or peritoneal 

 cavity is small, and they can l)e got rid of by the bacteriolytic action 

 of the blood-plasma or peritoneal liquid respectively. 



Through the toxines set free from the bacteriolysed organism, in 

 the latter case, a condition of chronic toxic poisoning of the animal 

 ensues. If, again, the blood-plasma has lost its bacteriolytic pro- 

 tective action completely, the organism not only passes the barrier 

 constituted by the wall of the bowel, but fructifies on the peritoneal 

 liquid, killing the animal with symptoms of acute toxic poisoning. 



It would thus appear that the sheep is a remarkable animal 

 in that its blood is highly protective at certain times of the year, 

 while at other times this protective influence is more or less com- 

 pletely lost. 



Whether such a relationship exists in a modified form in the 

 human blood with regard to certain pathogenic bacteria may be a 

 matter of question. Xo one has inquired into the subject, but, 

 judging from analogy, there seems little reason to suppose that such 

 an outstanding quality occurring in one mammal is not at least 

 represented in another. The fall of the leaf and the spring of the 

 year have always been held to be seasons of great susceptibility in 

 man to certain contagious and infectious diseases. May it not be that 

 the natural bactericidal qualities of the blood, as in the case of the 

 sheep, are lessened at these particular seasons ? various pathogenic 

 organisms being thus encouraged to grow upon the tissues or it may 

 be upon the surface of the various mucous membranes. 



Prevention. — When any one of the before-mentioned diseases is 

 thoroughly established, remedial measures are of little avail. In the 

 case of Braxy the course of the malady is so rapid that opportunity 

 is seldom afforded for the administration of what might be regarded 

 as curative agents, and in that of the others nothing in my ex- 

 perience has the slightest effect in staying the course of the disease. 



All efforts at amelioration of these scourges, therefore, must be 

 directed to prevention, must be of a prophylactic nature. From 



