VIII, B, 5 Barber: Infection of Achlya 381 



twenty-four hours the spore had germinated and put forth a 

 long hypha which grew rapidly within the host and formed septa. 



On the second day after inoculation the Aspergillus mycelium 

 had branched extensively, spreading through the infected hypha 

 and far into its branches. The invading hyphse tended to follow 

 the wall of the host, lying in the layer of protoplasm. The 

 Achlya was still living with motile protoplasm two days after 

 inoculation, but the protoplasm was becoming scanty. In many 

 places branches of the Aspergillus grew through the wall of 

 the still living host and penetrated the surrounding medium. 

 (Plate III.) 



Here the Aspergillus, apparently an ordinary saprophyte, 

 traverses the wall of the living host from within outward in 

 the same way that a true parasite enters. The penetration of 

 the wall is accomplished in both cases with little or no loss of 

 contents or immediate disturbance of the protoplasmic circula- 

 tion of the host. No case was observed of Aspergillus branches 

 outside penetrating a new Achlya filament. 



During the second day the Achlya filament died, filled with 

 the mycelium of the Aspergillus. There were no bacteria in 

 the neighborhood, and the death of the host was apparently due 

 to exhaustion of food. One or two days later branches of the 

 Aspergillus coming from the Achlya filament formed fruit stalks 

 and spores. 



In this experiment we have a saprophyte, or certainly a plant 

 not normally parasitic on Achlya, behaving much like a parasite 

 when its spores are mechanically introduced into the other plant. 



Yeast plants also grew well in the hyphse of Achlya growing 

 in pure culture. Both fungus spores and yeast plants are com- 

 paratively difficult to inoculate, since one must use a pipette 

 of relatively large size in order to admit these cells into it, and 

 such a pipette must necessarily make a large opening in the 

 wall of the filament inoculated. 



SUMMARY 



I. Achlya growing in pure culture is readily infected with 

 Bacillus pyocyaneus, cholera vibrios, or the bacilli of dysentery 

 and of bubonic plague, when inoculated into the cell cavity. 



II. Pyocyaneus or cholera-infected filaments usually die within 

 twenty-four hours after inoculation. Filaments infected with 

 dysentery bacilli sometimes survive five or six days at a room 

 temperature of from 27° to 31°. 



III. Yeast plants and spores of Aspergillus also develop in 



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