Abstract: The invention disclosed comprises a process and apparatus for the cultivation of cells, and having particular application to the product of mushroom spawn, in which a particulate substrate, water and, in some cases chalk, are introduced into a rotary blender and thoroughly mixed and sterilized at a temperature of about 250.degree. F. The mixture is cooled in the blender and a cell line inoculum is sterilely introduced into the mixture and thoroughly blended with the substrate. The blended inoculum and substrate are transferred in a sterile air flow from the blender to sterile containers which include a breathing strip in which the cells lines are incubated. The apparatus includes the combination of blender, transfer means and a clean room for filling the sterile containers.