土壌中（埴壌土，pH 5.3-6.5，含水比30%）における植物病原性Pythium ultimum（宿主）と，菌間寄生者P. oligandrum（寄生者）の菌糸の相互作用を25℃で観察した．寄生者は，宿主への接触，密着・伸長，巻き付きと鈎形分枝による補捉，付着器形成に続いて侵入し，伸長または肥大後分枝して脱出し，宿主内および脱出した寄生者は有性と無性の繁殖構造を形成した．この繁殖構造が発芽して伸長した菌糸と宿主外へ脱出した寄生者の菌糸による近隣宿主への接触，捕捉，侵入，脱出，繁殖構造形成の繰返しが観察された．一方，寄生者と接触した宿主の部位はしばしば破裂した．宿主は寄生者の密着・伸長を受けると原形質が顆粒化し，捕捉・侵入を受けると若令でも隔壁を形成した．寄生者が宿主体内を伸長・肥大すると，宿主原形質は徐徐に消失し，溶菌が進行した．一部に原形質が残存する宿主菌糸，宿主の無性と有性の繁殖構造の形成が認められた．

　The sporangiophore of the fungus Phycomyces rotates in the clockwise direction as viewed from above when the sporangiophore is actively elongating and in the counterclockwise direction when the sporangiophore starts elongation in the newly-established growth-zone beneath the sporangium. The rotation of the piloboloid-mutant sporangiophore, the growth of which is characterized by a gradual cessation of elongation and by a gradual increase in radial expansion in the growth zone, reverses its direction from clockwise to counterclockwise during the period of increased radial expansion. The rotation of these sporangiophores can be explained by the reorientation of the microfibrils in the growth zone. The sporangiophore of a closely-related fungus Pilobolus, which also expands at the subsporangial vesicle, rotates in the clockwise direction when elongation recommenced in the newly-established growth zone just beneath the subsporangial vesicle. The rotation of this fungus may also be interpreted in terms of behavior of microfibrils. The methods for measurement and terminological expression of rotational behavior were also proposed.