Little is known about funda­mental mechanisms of growth control on the growth ff single or small groups of cells of the higher plants. Study of these effects in vitro requires the knowledge of the primary conditions for growth in vitro. In this work a procedure was outlined and used in an ef­fort to establish a basis for the standard procedure. Also the associated effects of the physical, and to some extent, the chemical environment on the growth of the proembryo and prothallium. of Linus were studied. / Thesis / Master of Science (MS)