Abstract
A new cryptocephal (crc) phenocopy agent is described for Drosophila melanogaster. The morphogenetic action of this agent, hydroxyproline (OHP) is compared to that of another crc phenocopy agent, glucosamine HCI (GA). The sensitive period for OHP lasts somewhat longer than that of GA. A comparison of the effect of GA and OHP on two strains of Drosophila showed that a relatively high strain sensitivity to one agent could be accompanied by a low response to the other. It is concluded that the developmental buffering of the agents is controlled by different genes.