1. Effect of nitrogenous compounds on the morphological differentiation of gametophyte of a fern, Dryopteris erythrosora, was investigated. Studies were carried out for the most part about the effects of nitrogenous compounds on “the two-dimensional differentiation” (conversion of the filamentous organization to the plate-like one). (i) In the nitrogen deficient culture the two-dimensional differentiation does not occur. (ii) NH4-salts are more effective than NO3-salts for the induction of the two-dimensional differentiation. NaNO3 reveals many deleterious effects. (iii) Several amino acids, which were used in this experiment, are classified in the following three groups according to their effects on the two-dimensional differentiation: a) those which induce the differentiation earlier than in the standard culture, b) later than in the standard, and c) the same as in the standard. 2. Analyses of amino acids both in the alcohol soluble fraction and in residual fraction were carried out at various stages of the gametophyte differentiation. Ten amino acids and two amides were detected in the alcohol soluble fraction; some of them showed characteristic changes in their amounts corresponded to the development of the morphological differentiation. Twenty amino acids including 4 substances of unidentified nature were detected in the residual fraction; significance of the change in their amount is discussed in connection with the two-dimensional differentiation. 3. The author's view (1958) that the qualitative change of protein may be responsible for the induction of the two-dimensional differentiation, is also supported by the results of the present experiments.
The development of sorus of Undaria undarioides (Yendo) Okamura, Eckloniopsis radicosa (Kjellman) Okamura and Ecklonia cava Kjellman has been observed. In all of three species both the zoosporangia and paraphyses originate from the meristoderm of the blade. In Undaria undarioides and Ecklonia cava, the mode of the development of sorus is Laminaria- type. In Eckloniopsis radicosa, the cuticle of the superficial cells is stripped on the way of sorus development. This fact seems to suggest that Eckloniopsis radicosa is identical in the mode of sorus development with Chorda filum