Observations on the Structure of the Zoospores ofVaucheria, II

Abstract

Sections of Vaucheria zoospores fixed at various stages have been examined in the electron microscope. Changes in the organization of the cytoplasm and the redistribution of its organelles are described and correlated with observations of living spores during their transformation into vegetative cells. In particular, proof is given that the disappearance of the cilia involves the withdrawal of the fibrillar axes of these organs into the cytoplasm and that the disappearance of the transparent outer zone of the motile spore involves the inward movement of special cytoplasmic vesicles which form a main component of this layer. As a result of improved fixation new structural details are given, the most important of which concern the cytoplasmic matrix, the boundary membranes of the nuclei, the golgi bodies and their relation to mitochondria, and the internal structure of the chloroplasts. With the aid of serial sections it is shown that the internal laminae of the chloroplast are connected with each other in a special manner.