Studies on Horizontal Growth of Conchocelis

The direction of light determines to a considerable extent the direction of growth in plant development. However, as to the algae which live in the water, the relation between light and growth direction has never been reported. In this paper, the authors studied on the horizontal growth of Conchocelis filaments and conchosporangial branches. The carpospores of P. yezoensis and P. tenera were placed on Solen stricus and oyster shells as substrata, and their germlings were cultured under the room diffused light and under the one side light. Under the room diffused light, Conchocelis filaments developed into pinnately branched and radiating filamentous thalli by apical growth. On the other hand, under one side light Conchocelis filaments and conchosporangial branches curved toward the light, showing distinctly positive phototropism.ノリ糸状体の水平生長に関して1個体を連続的に観察し,とくに光の方向を一定にして培養して,光と生長方向との関係をしらべた。1.室内散光下では糸状体は放射状に生育し,光と生長方向とには明らかな関係はみられない。2.一定方向の光で糸状体を培養すると,枝や殻胞殻子嚢枝は光の来る方向に屈曲し,側枝は光の側に新生される。3.すなわち,ノリ糸状体は光に対して明瞭な正の屈光性を示す