BEHAVIOR OF BACTERIOPHAGE IN DISEASE 487 



countering on a mucous surface a bacterium which it can not digest, 

 it phagocytizes it and carries it into the body. 



The bacteriophage protobe is a "salutary agent" when it causes 

 bacteriophagy in vivo; it is harmful to the individual who harbors it 

 when it forms a symbiotic relationship with a microbe which has an 

 acquired resistance to bacteriophagy. Such a symbiosis causes the 

 bacterium to suddenly acquire a resistance to phagocytosis, and it also 

 confers upon the bacterium the property of yielding "ultrabacterial" 

 filtrable forms, as appears to be the case in typhus fever, in typhoid 

 fever, and doubtless in other diseases. 



Within the body, there are not "reactions of defense;" there are simply 

 reactions, salutary or harmful according to the conditions under which 

 they take place. 



8. THE BACTERIOPHAGE IN PLANTS 



We know that on the roots of the Leguminosae we find nodules which 

 are due to the reaction of the plant to the presence of nitrifying bacteria, 

 B. radicicola. Here there is a symbiosis between the plant and the 

 bacterium, but it is a symbiosis in the true sense of the word, that is to 

 say, it is a mitigated parasitism. B. radicicola attempts to invade the 

 tissues of the plant but there is some "cause" which prevents this 

 invasion. 



Many authors have sought for this cause. They have observed that 

 in certain cases an alteration of the bacteria takes place; the plant, 

 they have said, imposes a teratological form on the bacterium, and 

 sometimes succeeds in eliminating it. 



Zinzer* inoculated cultures of B. radicicola into the stems of the 

 Leguminosae and found that the bacteria were destroyed without be- 

 coming implanted in the tissues. On the other hand, Giornini, while 

 studying the tumor of the olive tree, saw that the "tissues" in the region 

 of the tumor possessed agglutinating properties, and even destructive 

 properties, for the pathogenic bacterium. 



In this destruction, the tissues of the plant did not effect the phe- 

 nomenon without some agency, and the nature of this has been shown 

 by the work of the Dutch authors, Gerretsen, Sack, Gryns, and 

 Sohngen,22** 



They worked with the nodules found on the roots of clover, sarrandella 

 and lupin. They washed these nodules in a 1 per cent mercuric chloride 



* Zinzer. — ^Ueber das verhalten von Bakterien, insbesondere von Knollschen- 

 bakterien in lebenden pflanzlichen Geweben. Jahrb. f. Wiss. Bot., 1897, 30, 423. 



