A SUPPOSEDLY INJURIOUS FUNGUS. 65 



though occasionally two and rarely three were found together in the 

 same cell. They were 0.0007 to 0.0008 of an inch (18 to 20 /x) in 

 diameter, and in optical section showed an outer ring and an inner 

 ring, with G, 7, 8, 9, or 10 introrse scallops in the hj^aline zone be- 

 tween them, the space within the inner ring being granular. These 

 are evidently spores with a very thick wall, marked with a few large 

 pits or depressions, and granular contents in the cell cavity. In what 

 appeared to be later stages of development of these spores, the diam- 

 eter was slightly larger, the wall was thin, the pits had disappeared, 

 and the granular contents had become organized into minute spher- 

 ical bodies, apparently incipient swarm spores, about 0.0001 of an 

 inch (2 /x) in diameter, approximately one-tenth the diameter of the 

 spore itself. Several pf these large, thin-walled spores had put out a 

 short germination tube and lost their contents, the spore remaining 

 entirel}' hyaline and empty. 



It was thought at first that these might be the reproductive bodies 

 of the mycorrhizal fungus of the blueberry, but a careful search 

 failed to shoW' any connection between the two. It was observed, 

 however, that in the rootlets containing the spores the interior cells 

 usuallj^ presented a diseased appearance, the whole rootlet sometimes 

 showing a brown streak down its middle, due to the decomposition of 

 the vessels and wood cells. The inquiry into the nature of the spores 

 was not pursued further, but the conditions strongly suggested that 

 the spores Avere those of a parasitic fungus occupying the interior of 

 the roots and causing, or associated with, their death and decomposi- 

 tion. The spores themselves bear a strong resemblance to the resting 

 spores of Asteroeystis radieh, a parasitic fungus of the family Chytri- 

 diacese. This fungus occurs in Europe in the roots of various plants, 

 particularly flax, in which it is the cause of a serious disease." 



If an explanation is sought for the injurious effect of lime on 

 the growth of the blueberry, the observations already made indicate 

 the propriety of a careful study of this large-spored fungus, with 

 special reference to the effect of lime in stimulating its growth and 

 the growth of the other organisms of decay associated with it. 



<26) Pots containing blieberry plants should be plunged in sand or other 

 material that will furnish constant moisture and good aeration. 



Although the plunging of earthen pots nearly to the rim in some 

 moisture-holding material, such as sand, sphagnum, or peat, had been 

 practiced for various purposes in several of the earlier cultures, 

 and had been found essential (as stated on p. 60) for 2-inch pot 

 cultures if rapid and uniform growth was to be secured, nevertheless 

 the importance of applying the same jiractice to larger pots was not 



"Marehal, Eniile. Recherehes Biologiques sur une Chytriclinee Parasite 

 du Lin. Bulletin de I'Agricnltnre, Brussels, vol. 16, 1900, pp. 511-554. 



54708°— Bull. 193—10- 5 



