10 H. L. Russell. 



but did not seem to be able to spread throughout plants which were 

 not its natural host. 



From the above considerations it will be seen that there is no 

 reasonable ground to support the hypothesis that the bacterial distri- 

 bution is purely physical. 



As no actual openings are known to exist in the walls of these 

 cells (if we except the very minute pores through which the plasmic 

 strands pass), it is difficult to understand how the bacteria are able 

 thus to spread from cell to cell unless they possess the power of 

 penetrating the cell wall by the action of vital forces. 



This ability would require physiological activity which could not 

 be present unless they were able to exercise their ordinary metabolic 

 functions. 



This penetrative power, among certain forms, is noteworthy when 

 we compare it with the results obtained by injecting different species 

 into the animal body. 



Von Fodor 1 found that when B. termo, B. subtilis and B. mega- 

 terium were introduced in large numbers into the jugular vein 

 of a living rabbit, they disappeared completely after a lapse of four 

 hours. 



Wyssokowitsch 2 also determined that the time necessary to com- 

 pletely destroy all bacteria contained in one c.c. of culture fluid, 

 when introduced into the animal body, varied from 15 min. with 

 Spir. tyrogenum to 7 hours with B. acidi lactici. 



The rapid disposal of these forms in the animal body is correlated, 

 as Nuttall 8 has shown, with the germicidal property of the blood- 

 serum. The action of plant-tissue upon bacteria* is in no case com- 

 parable to this, and would suggest that the plant is not protected in 

 a similar manner. This point will, however, be considered in detail 

 under another head. 



The possible explanation for the upward distribution of germs 

 may rest upon the principle that growth always follows the lines of 

 least resistance. Not only are food materials more abundant in the 

 rapidly growing apex, but the thinner and less developed cellulose 

 walls offer much less resistance to the spread of the germs than the 

 more matured cell-membranes of the older tissue. 



1 Von Fodor : Arch. f. Hyg. IV (1886), 129. 



2 Wyssokowitsch : Zeit. f. Hyg. I (1886), 3. 

 3 Nuttall: Zeit. f. Hyg. IV (1888), 353. 



