THE ALIMENTARY CANAL AS A SOURCE OF CONTAGION 27 



channel 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 finds entrance to the blood-stream or 

 peritoneal cavity is small, and they can be 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 have lost its bacteriolytic, 

 protective, 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 very remarkable animal in 

 respect of its blood being highly protective at certain times of the year, 

 while at other times this protective influence is more or less completely 

 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. No one has inquired into the subject, but, judging from 

 analogy, there seems little reason to suppose that such a remarkable 

 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 to certain contagious and infectious 

 diseases. May it not be that the natural bactericidal properties 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. 



The Toxines bound up with the Bacillus, — The essentially toxic 

 substance of the Louping-ill bacillus seems to be bound up with the 

 bacillus itself, and not to be shed into the liquid of culture. When a 

 culture of the bacillus is made upon glucose-beef-tea, the culture 

 filtered, and the filtrate injected subcutaneously in large quantity and 

 on several occasions into the sheep, the operation does not call forth 

 any symptoms ; the sheep seems to remain quite unaltered in its 

 condition. 



Seeing that the symptoms are apparently caused by the solution of 

 the bacilli, which find their way into the blood or lymph from the 

 intestine, and whose toxines are thus liberated, it occurred to me that 



(27) 



