The aim of the Biobloc experiment is to determine the biological effects of cosmic rays. Biobloc is a stack made up of biological layers and physical detectors (nuclear emulsions and plastic). Artemia eggs and tobacco seeds are used by French workers. Irradiation by cosmic heavy ions induces a late developmental inhibition of Artemia eggs. A light increase of emergence rate is observed for the non-hit eggs. The results are compared with those of previous space experiments. Investigations on tobacco seeds are in progress.