54 The Farmer's Veterinary Adviser. 



time the germ triumphs in the struggle for existence, and a 

 grave or mortal disease ia the consequence. When, how- 

 ever, the animal cells and nuclei are inured to the action of 

 this disease-poison by a former attack, they have acquired 

 an insusceptibility to it, and in spite of it retain all their 

 native vitality and vigor, so that the disease-germs which 

 are introduced fall easy victims to the devouring animal 

 cells. 



This position is further sustained by the fact that many 

 virulent liquids, introduced in small amount into the blood, 

 quickly perish, whereas if introduced into the tissues they 

 survive, multiply, and generate disease. In the blood, the 

 attacking party of disease-germs is confronted in rapid 

 succession by the endless myriads of actively moving blood- 

 globules, and in the resultant struggle the countless num- 

 bers of strong animal cells triumph, and the invading dis- 

 ease-germs are devoured. When the disease-germ is planted 

 in the tissues the case is reversed. Here the animal cells 

 (nuclei) are immovably fixed in the tissues which they sei-ve 

 to build up, so that the whole force of the invading germs 

 is thrown upon a few. The poisonous chemical products 

 (ptomaines) lower their vitality, so that they can no longer 

 successfully i-esist the morbid germs, and the latter increase 

 rapidly, pour their depressing products onward through the 

 lymphatic vessels into the blood and system at large, and 

 finally debilitate the whole, so that the germ finds no effec- 

 tive resistance at any point, not even in the blood itself. 

 Thus the disease, which is at first local, becomes general, be- 

 cause the animal cells at the point where the vims was im- 

 planted, had not the power to resist the depressing influence 

 of the germ products, and the germ was allowed to increase 

 in numbers and force. 



Another consideration sustains this theory. The protec- 

 tion conferred upon a system by a fii-st attack of a disease- 

 germ is to be trusted even where the diseased processes 



