The development of coremia: I. Penicillium claviforme

Abstract

The number and distribution of coremium initials and of mature coremia of Penicillium claviforme is markedly influenced by illumination and nutrition. Illumination also determines the size and form of coremia, the photosensitive period being early in the elongation of the coremium stalk, during the first 2 mm. of growth. At this stage also, and at no other, the coremia exhibit strong positive phototropism. Stalk elongation occurs by apical growth, and proceeds at a uniform rate until maximum height is reached. Following the cessation of growth, the differentiation of the head takes place, and sporulation follows. If the tips of growing coremia are amputated, regeneration occurs, and the tip briefly reverts to the photosensitive state characteristic of young coremia. A technique for growing excised coremia is described.