Cobs may be retted by the action of microorganisms, so that the network of vascular bundles is freed of all other tissue and left intact for study. Other methods of preparing cobs for study consist of covering them with 72% commercial-strength H2SO4, and treating them with 40-41% commercial-strength HCl. Cobs studied by these methods show no evidence that the maize ear originated by the fusion cf simpler spikes.