EFFECT OF 2,4-DICHLOROPHENOXYACETIC ACID ON THE FINE STRUCTURE OF CHLORELLA PYRENOIDOSA CHICK1

Chlorella pyrenoidosa Chick cells grown in liquid culture containing 5 × 10^?3M sodium 2,4-dichloro-phenoxyacetic acid exhibited vesiculation of the plasma membrane, mitochondrial swelling with disorganization of cristae, disruption of the chloroplast lamellar system, and dictyosomes with irregularly swollen cisternae. Ultrastructural details previously not reported for species of Chlorella were also observed: (1) presence of a crystalline pyrenoid with an 80 A periodicity, (2) a nucleolus made up of ribosome-like particles, and (3) smaller ribosomes in the chloroplast and mitochondria than in the cytoplasm.