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parasite preying upon the Helminthosporium mycelium; but numerous 

 tests convinced me that such was not the case, but that what really occurs 

 is that the old aerial mycelium dissolves (probably by auto-digestion). All 

 stages of this disorganization can be followed under the immersion leris in 

 stained preparations, where the disorganized filament stains wifn the gen- 

 tian violet but is seen to be amorphous and without protoplasmic content. 

 These phenomena appear to be limited to the aerial mycelium, but were 



FIG. 7. Various views (a and b, low power, c o, high power) of mycelium of H. No. 1 in 

 senescence: o and b showing dissolution to fine threads, b with a conidipphore still attached; 

 c h and m, empty mycelial cells adjacent to cells nearly dissolved; i and j, protoplasmic 

 cells adjacent to empty cells; k and I, fine mycelial outgrowths from protoplasmic cells; and 

 o, fine mycelia-l threads growing from the protoplasmic cells and through old empty cells; p, 

 bits of mycelium, as seen with the immersion lens, showing the nuclei. 



observed on many strains of Helminthosporium. Autodigestion of my- 

 celium doubtless occurs in the case of wood-rotting fungi, as is evidenced 

 by the absence of mycelium where it was previously known to be, and it 

 may be of common occurrence in other fungi. It certainly occurs when 

 two hyphae join by anastomosis, and in the union of sexual organs. Grow- 

 ing-through of the mycelium, as noted above, and even conidia-formation 

 within the old cell are common in Saprolegnia, and have been noted in 



