376 '^^^ Philippine Journal of Science isu 



take place inside of the infected mycelium and none in the 

 medium around it; or, if desired, to have one kind of organism 

 growing in the host and another kind outside. To avoid inocu- 

 lating the medium outside of the plant some special precautions 

 are necessary. A hanging drop of the bacterium is made outside 

 of the paraffin barrier, and beside it is placed a drop of sterile 

 water or agar. After supplying the pipette with the necessary 

 dose it is withdrawn from the bacteria and passed through the 

 water or agar drop to remove from its surface any adhering 

 bacteria. After inoculating the fungus the tip must be with- 

 drawn very slowly and cautiously in order to prevent the forc- 

 ing out of any of the injected bacteria by the cell pressure. 

 In case some bacteria are left outside in the medium, it is often 

 possible to remove them with an ordinary capillary pipette. 

 If too numerous or scattered to be removed in this way, their 

 growth may be restricted or their effects diminished by fre- 

 quently withdrawing the old medium and substituting new, or 

 by adding some specific serum unfavorable to the development 

 of the bacterium. 



In the following experiments, bacteria pathogenic to animals 

 were inoculated in order to test their effects on plant protoplasm. 

 Of motile forms, Bacillus pyocyaneus and the vibrios of Asiatic 

 cholera were tested; and of the nonmotile, the bacillus of 

 dysentery, Shiga-Kruse type, and the bacillus of bubonic plague. 



With Bacillus pyocyaneus some 14 successful inoculations were 

 made, the majority in pure cultures of Achlya in hanging drop 

 at a room temperature of from 27 to 31° C. Under these 

 conditions infection usually followed the inoculating of even very 

 small doses, and the death of the filament occurred within twenty- 

 four hours. Not only the hypha at the point of inoculation 

 become infected, but any branches not plugged off from the 

 inoculated filament soon became swarming to their finest endings 

 with actively motile bacilli. Noninfected filaments often re- 

 mained in good condition in the same hanging drop. The cause 

 of the death of the infected filaments was, apparently, primarily 

 due to exhaustion of nutriment by the bacteria, since the proto- 

 plasm of the host often remained living and motile when the 

 bacilli were so numerous as to form practically an emulsion in 

 the vacuole. Bacillus pyocyaneus grown outside the mycelium in 

 an agar hanging drop may be tolerated two or three days. 



After the death of the filament the bacteria continued to grow, 

 packing the filament with densely crowded masses, and often 

 bursting through the wall and forming masses usually at the 

 tips of branches. (Plate I.) The whole infected filament takes 



